1 /* 2 * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2019, Azul Systems, Inc. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. Oracle designates this 9 * particular file as subject to the "Classpath" exception as provided 10 * by Oracle in the LICENSE file that accompanied this code. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 * or visit www.oracle.com if you need additional information or have any 24 * questions. 25 */ 26 27 package java.lang; 28 29 import java.io.InputStream; 30 import java.io.IOException; 31 import java.io.UncheckedIOException; 32 import java.io.File; 33 import java.lang.reflect.Constructor; 34 import java.lang.reflect.InvocationTargetException; 35 import java.net.URL; 36 import java.security.AccessController; 37 import java.security.AccessControlContext; 38 import java.security.CodeSource; 39 import java.security.PrivilegedAction; 40 import java.security.ProtectionDomain; 41 import java.security.cert.Certificate; 42 import java.util.ArrayDeque; 43 import java.util.Arrays; 44 import java.util.Collections; 45 import java.util.Deque; 46 import java.util.Enumeration; 47 import java.util.HashMap; 48 import java.util.HashSet; 49 import java.util.Hashtable; 50 import java.util.Map; 51 import java.util.NoSuchElementException; 52 import java.util.Objects; 53 import java.util.Set; 54 import java.util.Spliterator; 55 import java.util.Spliterators; 56 import java.util.Vector; 57 import java.util.WeakHashMap; 58 import java.util.concurrent.ConcurrentHashMap; 59 import java.util.function.Supplier; 60 import java.util.stream.Stream; 61 import java.util.stream.StreamSupport; 62 63 import jdk.internal.loader.BuiltinClassLoader; 64 import jdk.internal.perf.PerfCounter; 65 import jdk.internal.loader.BootLoader; 66 import jdk.internal.loader.ClassLoaders; 67 import jdk.internal.misc.Unsafe; 68 import jdk.internal.misc.VM; 69 import jdk.internal.ref.CleanerFactory; 70 import jdk.internal.reflect.CallerSensitive; 71 import jdk.internal.reflect.Reflection; 72 import sun.reflect.misc.ReflectUtil; 73 import sun.security.util.SecurityConstants; 74 75 /** 76 * A class loader is an object that is responsible for loading classes. The 77 * class {@code ClassLoader} is an abstract class. Given the <a 78 * href="#binary-name">binary name</a> of a class, a class loader should attempt to 79 * locate or generate data that constitutes a definition for the class. A 80 * typical strategy is to transform the name into a file name and then read a 81 * "class file" of that name from a file system. 82 * 83 * <p> Every {@link java.lang.Class Class} object contains a {@link 84 * Class#getClassLoader() reference} to the {@code ClassLoader} that defined 85 * it. 86 * 87 * <p> {@code Class} objects for array classes are not created by class 88 * loaders, but are created automatically as required by the Java runtime. 89 * The class loader for an array class, as returned by {@link 90 * Class#getClassLoader()} is the same as the class loader for its element 91 * type; if the element type is a primitive type, then the array class has no 92 * class loader. 93 * 94 * <p> Applications implement subclasses of {@code ClassLoader} in order to 95 * extend the manner in which the Java virtual machine dynamically loads 96 * classes. 97 * 98 * <p> Class loaders may typically be used by security managers to indicate 99 * security domains. 100 * 101 * <p> In addition to loading classes, a class loader is also responsible for 102 * locating resources. A resource is some data (a "{@code .class}" file, 103 * configuration data, or an image for example) that is identified with an 104 * abstract '/'-separated path name. Resources are typically packaged with an 105 * application or library so that they can be located by code in the 106 * application or library. In some cases, the resources are included so that 107 * they can be located by other libraries. 108 * 109 * <p> The {@code ClassLoader} class uses a delegation model to search for 110 * classes and resources. Each instance of {@code ClassLoader} has an 111 * associated parent class loader. When requested to find a class or 112 * resource, a {@code ClassLoader} instance will usually delegate the search 113 * for the class or resource to its parent class loader before attempting to 114 * find the class or resource itself. 115 * 116 * <p> Class loaders that support concurrent loading of classes are known as 117 * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class 118 * loaders and are required to register themselves at their class initialization 119 * time by invoking the {@link 120 * #registerAsParallelCapable ClassLoader.registerAsParallelCapable} 121 * method. Note that the {@code ClassLoader} class is registered as parallel 122 * capable by default. However, its subclasses still need to register themselves 123 * if they are parallel capable. 124 * In environments in which the delegation model is not strictly 125 * hierarchical, class loaders need to be parallel capable, otherwise class 126 * loading can lead to deadlocks because the loader lock is held for the 127 * duration of the class loading process (see {@link #loadClass 128 * loadClass} methods). 129 * 130 * <h2> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h2> 131 * 132 * The Java run-time has the following built-in class loaders: 133 * 134 * <ul> 135 * <li><p>Bootstrap class loader. 136 * It is the virtual machine's built-in class loader, typically represented 137 * as {@code null}, and does not have a parent.</li> 138 * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}. 139 * All <em>platform classes</em> are visible to the platform class loader 140 * that can be used as the parent of a {@code ClassLoader} instance. 141 * Platform classes include Java SE platform APIs, their implementation 142 * classes and JDK-specific run-time classes that are defined by the 143 * platform class loader or its ancestors. 144 * <p> To allow for upgrading/overriding of modules defined to the platform 145 * class loader, and where upgraded modules read modules defined to class 146 * loaders other than the platform class loader and its ancestors, then 147 * the platform class loader may have to delegate to other class loaders, 148 * the application class loader for example. 149 * In other words, classes in named modules defined to class loaders 150 * other than the platform class loader and its ancestors may be visible 151 * to the platform class loader. </li> 152 * <li><p>{@linkplain #getSystemClassLoader() System class loader}. 153 * It is also known as <em>application class loader</em> and is distinct 154 * from the platform class loader. 155 * The system class loader is typically used to define classes on the 156 * application class path, module path, and JDK-specific tools. 157 * The platform class loader is a parent or an ancestor of the system class 158 * loader that all platform classes are visible to it.</li> 159 * </ul> 160 * 161 * <p> Normally, the Java virtual machine loads classes from the local file 162 * system in a platform-dependent manner. 163 * However, some classes may not originate from a file; they may originate 164 * from other sources, such as the network, or they could be constructed by an 165 * application. The method {@link #defineClass(String, byte[], int, int) 166 * defineClass} converts an array of bytes into an instance of class 167 * {@code Class}. Instances of this newly defined class can be created using 168 * {@link Class#newInstance Class.newInstance}. 169 * 170 * <p> The methods and constructors of objects created by a class loader may 171 * reference other classes. To determine the class(es) referred to, the Java 172 * virtual machine invokes the {@link #loadClass loadClass} method of 173 * the class loader that originally created the class. 174 * 175 * <p> For example, an application could create a network class loader to 176 * download class files from a server. Sample code might look like: 177 * 178 * <blockquote><pre> 179 * ClassLoader loader = new NetworkClassLoader(host, port); 180 * Object main = loader.loadClass("Main", true).newInstance(); 181 * . . . 182 * </pre></blockquote> 183 * 184 * <p> The network class loader subclass must define the methods {@link 185 * #findClass findClass} and {@code loadClassData} to load a class 186 * from the network. Once it has downloaded the bytes that make up the class, 187 * it should use the method {@link #defineClass defineClass} to 188 * create a class instance. A sample implementation is: 189 * 190 * <blockquote><pre> 191 * class NetworkClassLoader extends ClassLoader { 192 * String host; 193 * int port; 194 * 195 * public Class findClass(String name) { 196 * byte[] b = loadClassData(name); 197 * return defineClass(name, b, 0, b.length); 198 * } 199 * 200 * private byte[] loadClassData(String name) { 201 * // load the class data from the connection 202 * . . . 203 * } 204 * } 205 * </pre></blockquote> 206 * 207 * <h3> <a id="binary-name">Binary names</a> </h3> 208 * 209 * <p> Any class name provided as a {@code String} parameter to methods in 210 * {@code ClassLoader} must be a binary name as defined by 211 * <cite>The Java™ Language Specification</cite>. 212 * 213 * <p> Examples of valid class names include: 214 * <blockquote><pre> 215 * "java.lang.String" 216 * "javax.swing.JSpinner$DefaultEditor" 217 * "java.security.KeyStore$Builder$FileBuilder$1" 218 * "java.net.URLClassLoader$3$1" 219 * </pre></blockquote> 220 * 221 * <p> Any package name provided as a {@code String} parameter to methods in 222 * {@code ClassLoader} must be either the empty string (denoting an unnamed package) 223 * or a fully qualified name as defined by 224 * <cite>The Java™ Language Specification</cite>. 225 * 226 * @jls 6.7 Fully Qualified Names 227 * @jls 13.1 The Form of a Binary 228 * @see #resolveClass(Class) 229 * @since 1.0 230 * @revised 9 231 * @spec JPMS 232 */ 233 public abstract class ClassLoader { 234 235 private static native void registerNatives(); 236 static { 237 registerNatives(); 238 } 239 240 // The parent class loader for delegation 241 // Note: VM hardcoded the offset of this field, thus all new fields 242 // must be added *after* it. 243 private final ClassLoader parent; 244 245 // class loader name 246 private final String name; 247 248 // the unnamed module for this ClassLoader 249 private final Module unnamedModule; 250 251 // a string for exception message printing 252 private final String nameAndId; 253 254 /** 255 * Encapsulates the set of parallel capable loader types. 256 */ 257 private static class ParallelLoaders { 258 private ParallelLoaders() {} 259 260 // the set of parallel capable loader types 261 private static final Set<Class<? extends ClassLoader>> loaderTypes = 262 Collections.newSetFromMap(new WeakHashMap<>()); 263 static { 264 synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); } 265 } 266 267 /** 268 * Registers the given class loader type as parallel capable. 269 * Returns {@code true} is successfully registered; {@code false} if 270 * loader's super class is not registered. 271 */ 272 static boolean register(Class<? extends ClassLoader> c) { 273 synchronized (loaderTypes) { 274 if (loaderTypes.contains(c.getSuperclass())) { 275 // register the class loader as parallel capable 276 // if and only if all of its super classes are. 277 // Note: given current classloading sequence, if 278 // the immediate super class is parallel capable, 279 // all the super classes higher up must be too. 280 loaderTypes.add(c); 281 return true; 282 } else { 283 return false; 284 } 285 } 286 } 287 288 /** 289 * Returns {@code true} if the given class loader type is 290 * registered as parallel capable. 291 */ 292 static boolean isRegistered(Class<? extends ClassLoader> c) { 293 synchronized (loaderTypes) { 294 return loaderTypes.contains(c); 295 } 296 } 297 } 298 299 // Maps class name to the corresponding lock object when the current 300 // class loader is parallel capable. 301 // Note: VM also uses this field to decide if the current class loader 302 // is parallel capable and the appropriate lock object for class loading. 303 private final ConcurrentHashMap<String, Object> parallelLockMap; 304 305 // Maps packages to certs 306 private final Map <String, Certificate[]> package2certs; 307 308 // Shared among all packages with unsigned classes 309 private static final Certificate[] nocerts = new Certificate[0]; 310 311 // The classes loaded by this class loader. The only purpose of this table 312 // is to keep the classes from being GC'ed until the loader is GC'ed. 313 private final Vector<Class<?>> classes = new Vector<>(); 314 315 // The "default" domain. Set as the default ProtectionDomain on newly 316 // created classes. 317 private final ProtectionDomain defaultDomain = 318 new ProtectionDomain(new CodeSource(null, (Certificate[]) null), 319 null, this, null); 320 321 // Invoked by the VM to record every loaded class with this loader. 322 void addClass(Class<?> c) { 323 classes.addElement(c); 324 } 325 326 // The packages defined in this class loader. Each package name is 327 // mapped to its corresponding NamedPackage object. 328 // 329 // The value is a Package object if ClassLoader::definePackage, 330 // Class::getPackage, ClassLoader::getDefinePackage(s) or 331 // Package::getPackage(s) method is called to define it. 332 // Otherwise, the value is a NamedPackage object. 333 private final ConcurrentHashMap<String, NamedPackage> packages 334 = new ConcurrentHashMap<>(); 335 336 /* 337 * Returns a named package for the given module. 338 */ 339 private NamedPackage getNamedPackage(String pn, Module m) { 340 NamedPackage p = packages.get(pn); 341 if (p == null) { 342 p = new NamedPackage(pn, m); 343 344 NamedPackage value = packages.putIfAbsent(pn, p); 345 if (value != null) { 346 // Package object already be defined for the named package 347 p = value; 348 // if definePackage is called by this class loader to define 349 // a package in a named module, this will return Package 350 // object of the same name. Package object may contain 351 // unexpected information but it does not impact the runtime. 352 // this assertion may be helpful for troubleshooting 353 assert value.module() == m; 354 } 355 } 356 return p; 357 } 358 359 private static Void checkCreateClassLoader() { 360 return checkCreateClassLoader(null); 361 } 362 363 private static Void checkCreateClassLoader(String name) { 364 if (name != null && name.isEmpty()) { 365 throw new IllegalArgumentException("name must be non-empty or null"); 366 } 367 368 SecurityManager security = System.getSecurityManager(); 369 if (security != null) { 370 security.checkCreateClassLoader(); 371 } 372 return null; 373 } 374 375 private ClassLoader(Void unused, String name, ClassLoader parent) { 376 this.name = name; 377 this.parent = parent; 378 this.unnamedModule = new Module(this); 379 if (ParallelLoaders.isRegistered(this.getClass())) { 380 parallelLockMap = new ConcurrentHashMap<>(); 381 package2certs = new ConcurrentHashMap<>(); 382 assertionLock = new Object(); 383 } else { 384 // no finer-grained lock; lock on the classloader instance 385 parallelLockMap = null; 386 package2certs = new Hashtable<>(); 387 assertionLock = this; 388 } 389 this.nameAndId = nameAndId(this); 390 } 391 392 /** 393 * If the defining loader has a name explicitly set then 394 * '<loader-name>' @<id> 395 * If the defining loader has no name then 396 * <qualified-class-name> @<id> 397 * If it's built-in loader then omit `@<id>` as there is only one instance. 398 */ 399 private static String nameAndId(ClassLoader ld) { 400 String nid = ld.getName() != null ? "\'" + ld.getName() + "\'" 401 : ld.getClass().getName(); 402 if (!(ld instanceof BuiltinClassLoader)) { 403 String id = Integer.toHexString(System.identityHashCode(ld)); 404 nid = nid + " @" + id; 405 } 406 return nid; 407 } 408 409 /** 410 * Creates a new class loader of the specified name and using the 411 * specified parent class loader for delegation. 412 * 413 * @apiNote If the parent is specified as {@code null} (for the 414 * bootstrap class loader) then there is no guarantee that all platform 415 * classes are visible. 416 * 417 * @param name class loader name; or {@code null} if not named 418 * @param parent the parent class loader 419 * 420 * @throws IllegalArgumentException if the given name is empty. 421 * 422 * @throws SecurityException 423 * If a security manager exists and its 424 * {@link SecurityManager#checkCreateClassLoader()} 425 * method doesn't allow creation of a new class loader. 426 * 427 * @since 9 428 * @spec JPMS 429 */ 430 protected ClassLoader(String name, ClassLoader parent) { 431 this(checkCreateClassLoader(name), name, parent); 432 } 433 434 /** 435 * Creates a new class loader using the specified parent class loader for 436 * delegation. 437 * 438 * <p> If there is a security manager, its {@link 439 * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method 440 * is invoked. This may result in a security exception. </p> 441 * 442 * @apiNote If the parent is specified as {@code null} (for the 443 * bootstrap class loader) then there is no guarantee that all platform 444 * classes are visible. 445 * 446 * @param parent 447 * The parent class loader 448 * 449 * @throws SecurityException 450 * If a security manager exists and its 451 * {@code checkCreateClassLoader} method doesn't allow creation 452 * of a new class loader. 453 * 454 * @since 1.2 455 */ 456 protected ClassLoader(ClassLoader parent) { 457 this(checkCreateClassLoader(), null, parent); 458 } 459 460 /** 461 * Creates a new class loader using the {@code ClassLoader} returned by 462 * the method {@link #getSystemClassLoader() 463 * getSystemClassLoader()} as the parent class loader. 464 * 465 * <p> If there is a security manager, its {@link 466 * SecurityManager#checkCreateClassLoader() 467 * checkCreateClassLoader} method is invoked. This may result in 468 * a security exception. </p> 469 * 470 * @throws SecurityException 471 * If a security manager exists and its 472 * {@code checkCreateClassLoader} method doesn't allow creation 473 * of a new class loader. 474 */ 475 protected ClassLoader() { 476 this(checkCreateClassLoader(), null, getSystemClassLoader()); 477 } 478 479 /** 480 * Returns the name of this class loader or {@code null} if 481 * this class loader is not named. 482 * 483 * @apiNote This method is non-final for compatibility. If this 484 * method is overridden, this method must return the same name 485 * as specified when this class loader was instantiated. 486 * 487 * @return name of this class loader; or {@code null} if 488 * this class loader is not named. 489 * 490 * @since 9 491 * @spec JPMS 492 */ 493 public String getName() { 494 return name; 495 } 496 497 // package-private used by StackTraceElement to avoid 498 // calling the overrideable getName method 499 final String name() { 500 return name; 501 } 502 503 // -- Class -- 504 505 /** 506 * Loads the class with the specified <a href="#binary-name">binary name</a>. 507 * This method searches for classes in the same manner as the {@link 508 * #loadClass(String, boolean)} method. It is invoked by the Java virtual 509 * machine to resolve class references. Invoking this method is equivalent 510 * to invoking {@link #loadClass(String, boolean) loadClass(name, 511 * false)}. 512 * 513 * @param name 514 * The <a href="#binary-name">binary name</a> of the class 515 * 516 * @return The resulting {@code Class} object 517 * 518 * @throws ClassNotFoundException 519 * If the class was not found 520 */ 521 public Class<?> loadClass(String name) throws ClassNotFoundException { 522 return loadClass(name, false); 523 } 524 525 /** 526 * Loads the class with the specified <a href="#binary-name">binary name</a>. The 527 * default implementation of this method searches for classes in the 528 * following order: 529 * 530 * <ol> 531 * 532 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class 533 * has already been loaded. </p></li> 534 * 535 * <li><p> Invoke the {@link #loadClass(String) loadClass} method 536 * on the parent class loader. If the parent is {@code null} the class 537 * loader built into the virtual machine is used, instead. </p></li> 538 * 539 * <li><p> Invoke the {@link #findClass(String)} method to find the 540 * class. </p></li> 541 * 542 * </ol> 543 * 544 * <p> If the class was found using the above steps, and the 545 * {@code resolve} flag is true, this method will then invoke the {@link 546 * #resolveClass(Class)} method on the resulting {@code Class} object. 547 * 548 * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link 549 * #findClass(String)}, rather than this method. </p> 550 * 551 * <p> Unless overridden, this method synchronizes on the result of 552 * {@link #getClassLoadingLock getClassLoadingLock} method 553 * during the entire class loading process. 554 * 555 * @param name 556 * The <a href="#binary-name">binary name</a> of the class 557 * 558 * @param resolve 559 * If {@code true} then resolve the class 560 * 561 * @return The resulting {@code Class} object 562 * 563 * @throws ClassNotFoundException 564 * If the class could not be found 565 */ 566 protected Class<?> loadClass(String name, boolean resolve) 567 throws ClassNotFoundException 568 { 569 synchronized (getClassLoadingLock(name)) { 570 // First, check if the class has already been loaded 571 Class<?> c = findLoadedClass(name); 572 if (c == null) { 573 long t0 = System.nanoTime(); 574 try { 575 if (parent != null) { 576 c = parent.loadClass(name, false); 577 } else { 578 c = findBootstrapClassOrNull(name); 579 } 580 } catch (ClassNotFoundException e) { 581 // ClassNotFoundException thrown if class not found 582 // from the non-null parent class loader 583 } 584 585 if (c == null) { 586 // If still not found, then invoke findClass in order 587 // to find the class. 588 long t1 = System.nanoTime(); 589 c = findClass(name); 590 591 // this is the defining class loader; record the stats 592 PerfCounter.getParentDelegationTime().addTime(t1 - t0); 593 PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); 594 PerfCounter.getFindClasses().increment(); 595 } 596 } 597 if (resolve) { 598 resolveClass(c); 599 } 600 return c; 601 } 602 } 603 604 /** 605 * Loads the class with the specified <a href="#binary-name">binary name</a> 606 * in a module defined to this class loader. This method returns {@code null} 607 * if the class could not be found. 608 * 609 * @apiNote This method does not delegate to the parent class loader. 610 * 611 * @implSpec The default implementation of this method searches for classes 612 * in the following order: 613 * 614 * <ol> 615 * <li>Invoke {@link #findLoadedClass(String)} to check if the class 616 * has already been loaded.</li> 617 * <li>Invoke the {@link #findClass(String, String)} method to find the 618 * class in the given module.</li> 619 * </ol> 620 * 621 * @param module 622 * The module 623 * @param name 624 * The <a href="#binary-name">binary name</a> of the class 625 * 626 * @return The resulting {@code Class} object in a module defined by 627 * this class loader, or {@code null} if the class could not be found. 628 */ 629 final Class<?> loadClass(Module module, String name) { 630 synchronized (getClassLoadingLock(name)) { 631 // First, check if the class has already been loaded 632 Class<?> c = findLoadedClass(name); 633 if (c == null) { 634 c = findClass(module.getName(), name); 635 } 636 if (c != null && c.getModule() == module) { 637 return c; 638 } else { 639 return null; 640 } 641 } 642 } 643 644 /** 645 * Returns the lock object for class loading operations. 646 * For backward compatibility, the default implementation of this method 647 * behaves as follows. If this ClassLoader object is registered as 648 * parallel capable, the method returns a dedicated object associated 649 * with the specified class name. Otherwise, the method returns this 650 * ClassLoader object. 651 * 652 * @param className 653 * The name of the to-be-loaded class 654 * 655 * @return the lock for class loading operations 656 * 657 * @throws NullPointerException 658 * If registered as parallel capable and {@code className} is null 659 * 660 * @see #loadClass(String, boolean) 661 * 662 * @since 1.7 663 */ 664 protected Object getClassLoadingLock(String className) { 665 Object lock = this; 666 if (parallelLockMap != null) { 667 Object newLock = new Object(); 668 lock = parallelLockMap.putIfAbsent(className, newLock); 669 if (lock == null) { 670 lock = newLock; 671 } 672 } 673 return lock; 674 } 675 676 // Invoked by the VM after loading class with this loader. 677 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) { 678 final SecurityManager sm = System.getSecurityManager(); 679 if (sm != null) { 680 if (ReflectUtil.isNonPublicProxyClass(cls)) { 681 for (Class<?> intf: cls.getInterfaces()) { 682 checkPackageAccess(intf, pd); 683 } 684 return; 685 } 686 687 final String packageName = cls.getPackageName(); 688 if (!packageName.isEmpty()) { 689 AccessController.doPrivileged(new PrivilegedAction<>() { 690 public Void run() { 691 sm.checkPackageAccess(packageName); 692 return null; 693 } 694 }, new AccessControlContext(new ProtectionDomain[] {pd})); 695 } 696 } 697 } 698 699 /** 700 * Finds the class with the specified <a href="#binary-name">binary name</a>. 701 * This method should be overridden by class loader implementations that 702 * follow the delegation model for loading classes, and will be invoked by 703 * the {@link #loadClass loadClass} method after checking the 704 * parent class loader for the requested class. 705 * 706 * @implSpec The default implementation throws {@code ClassNotFoundException}. 707 * 708 * @param name 709 * The <a href="#binary-name">binary name</a> of the class 710 * 711 * @return The resulting {@code Class} object 712 * 713 * @throws ClassNotFoundException 714 * If the class could not be found 715 * 716 * @since 1.2 717 */ 718 protected Class<?> findClass(String name) throws ClassNotFoundException { 719 throw new ClassNotFoundException(name); 720 } 721 722 /** 723 * Finds the class with the given <a href="#binary-name">binary name</a> 724 * in a module defined to this class loader. 725 * Class loader implementations that support loading from modules 726 * should override this method. 727 * 728 * @apiNote This method returns {@code null} rather than throwing 729 * {@code ClassNotFoundException} if the class could not be found. 730 * 731 * @implSpec The default implementation attempts to find the class by 732 * invoking {@link #findClass(String)} when the {@code moduleName} is 733 * {@code null}. It otherwise returns {@code null}. 734 * 735 * @param moduleName 736 * The module name; or {@code null} to find the class in the 737 * {@linkplain #getUnnamedModule() unnamed module} for this 738 * class loader 739 740 * @param name 741 * The <a href="#binary-name">binary name</a> of the class 742 * 743 * @return The resulting {@code Class} object, or {@code null} 744 * if the class could not be found. 745 * 746 * @since 9 747 * @spec JPMS 748 */ 749 protected Class<?> findClass(String moduleName, String name) { 750 if (moduleName == null) { 751 try { 752 return findClass(name); 753 } catch (ClassNotFoundException ignore) { } 754 } 755 return null; 756 } 757 758 759 /** 760 * Converts an array of bytes into an instance of class {@code Class}. 761 * Before the {@code Class} can be used it must be resolved. This method 762 * is deprecated in favor of the version that takes a <a 763 * href="#binary-name">binary name</a> as its first argument, and is more secure. 764 * 765 * @param b 766 * The bytes that make up the class data. The bytes in positions 767 * {@code off} through {@code off+len-1} should have the format 768 * of a valid class file as defined by 769 * <cite>The Java™ Virtual Machine Specification</cite>. 770 * 771 * @param off 772 * The start offset in {@code b} of the class data 773 * 774 * @param len 775 * The length of the class data 776 * 777 * @return The {@code Class} object that was created from the specified 778 * class data 779 * 780 * @throws ClassFormatError 781 * If the data did not contain a valid class 782 * 783 * @throws IndexOutOfBoundsException 784 * If either {@code off} or {@code len} is negative, or if 785 * {@code off+len} is greater than {@code b.length}. 786 * 787 * @throws SecurityException 788 * If an attempt is made to add this class to a package that 789 * contains classes that were signed by a different set of 790 * certificates than this class, or if an attempt is made 791 * to define a class in a package with a fully-qualified name 792 * that starts with "{@code java.}". 793 * 794 * @see #loadClass(String, boolean) 795 * @see #resolveClass(Class) 796 * 797 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int) 798 * defineClass(String, byte[], int, int)} 799 */ 800 @Deprecated(since="1.1") 801 protected final Class<?> defineClass(byte[] b, int off, int len) 802 throws ClassFormatError 803 { 804 return defineClass(null, b, off, len, null); 805 } 806 807 /** 808 * Converts an array of bytes into an instance of class {@code Class}. 809 * Before the {@code Class} can be used it must be resolved. 810 * 811 * <p> This method assigns a default {@link java.security.ProtectionDomain 812 * ProtectionDomain} to the newly defined class. The 813 * {@code ProtectionDomain} is effectively granted the same set of 814 * permissions returned when {@link 815 * java.security.Policy#getPermissions(java.security.CodeSource) 816 * Policy.getPolicy().getPermissions(new CodeSource(null, null))} 817 * is invoked. The default protection domain is created on the first invocation 818 * of {@link #defineClass(String, byte[], int, int) defineClass}, 819 * and re-used on subsequent invocations. 820 * 821 * <p> To assign a specific {@code ProtectionDomain} to the class, use 822 * the {@link #defineClass(String, byte[], int, int, 823 * java.security.ProtectionDomain) defineClass} method that takes a 824 * {@code ProtectionDomain} as one of its arguments. </p> 825 * 826 * <p> 827 * This method defines a package in this class loader corresponding to the 828 * package of the {@code Class} (if such a package has not already been defined 829 * in this class loader). The name of the defined package is derived from 830 * the <a href="#binary-name">binary name</a> of the class specified by 831 * the byte array {@code b}. 832 * Other properties of the defined package are as specified by {@link Package}. 833 * 834 * @param name 835 * The expected <a href="#binary-name">binary name</a> of the class, or 836 * {@code null} if not known 837 * 838 * @param b 839 * The bytes that make up the class data. The bytes in positions 840 * {@code off} through {@code off+len-1} should have the format 841 * of a valid class file as defined by 842 * <cite>The Java™ Virtual Machine Specification</cite>. 843 * 844 * @param off 845 * The start offset in {@code b} of the class data 846 * 847 * @param len 848 * The length of the class data 849 * 850 * @return The {@code Class} object that was created from the specified 851 * class data. 852 * 853 * @throws ClassFormatError 854 * If the data did not contain a valid class 855 * 856 * @throws IndexOutOfBoundsException 857 * If either {@code off} or {@code len} is negative, or if 858 * {@code off+len} is greater than {@code b.length}. 859 * 860 * @throws SecurityException 861 * If an attempt is made to add this class to a package that 862 * contains classes that were signed by a different set of 863 * certificates than this class (which is unsigned), or if 864 * {@code name} begins with "{@code java.}". 865 * 866 * @see #loadClass(String, boolean) 867 * @see #resolveClass(Class) 868 * @see java.security.CodeSource 869 * @see java.security.SecureClassLoader 870 * 871 * @since 1.1 872 * @revised 9 873 * @spec JPMS 874 */ 875 protected final Class<?> defineClass(String name, byte[] b, int off, int len) 876 throws ClassFormatError 877 { 878 return defineClass(name, b, off, len, null); 879 } 880 881 /* Determine protection domain, and check that: 882 - not define java.* class, 883 - signer of this class matches signers for the rest of the classes in 884 package. 885 */ 886 private ProtectionDomain preDefineClass(String name, 887 ProtectionDomain pd) 888 { 889 if (!checkName(name)) 890 throw new NoClassDefFoundError("IllegalName: " + name); 891 892 // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias 893 // relies on the fact that spoofing is impossible if a class has a name 894 // of the form "java.*" 895 if ((name != null) && name.startsWith("java.") 896 && this != getBuiltinPlatformClassLoader()) { 897 throw new SecurityException 898 ("Prohibited package name: " + 899 name.substring(0, name.lastIndexOf('.'))); 900 } 901 if (pd == null) { 902 pd = defaultDomain; 903 } 904 905 if (name != null) { 906 checkCerts(name, pd.getCodeSource()); 907 } 908 909 return pd; 910 } 911 912 private String defineClassSourceLocation(ProtectionDomain pd) { 913 CodeSource cs = pd.getCodeSource(); 914 String source = null; 915 if (cs != null && cs.getLocation() != null) { 916 source = cs.getLocation().toString(); 917 } 918 return source; 919 } 920 921 private void postDefineClass(Class<?> c, ProtectionDomain pd) { 922 // define a named package, if not present 923 getNamedPackage(c.getPackageName(), c.getModule()); 924 925 if (pd.getCodeSource() != null) { 926 Certificate certs[] = pd.getCodeSource().getCertificates(); 927 if (certs != null) 928 setSigners(c, certs); 929 } 930 } 931 932 /** 933 * Converts an array of bytes into an instance of class {@code Class}, 934 * with a given {@code ProtectionDomain}. 935 * 936 * <p> If the given {@code ProtectionDomain} is {@code null}, 937 * then a default protection domain will be assigned to the class as specified 938 * in the documentation for {@link #defineClass(String, byte[], int, int)}. 939 * Before the class can be used it must be resolved. 940 * 941 * <p> The first class defined in a package determines the exact set of 942 * certificates that all subsequent classes defined in that package must 943 * contain. The set of certificates for a class is obtained from the 944 * {@link java.security.CodeSource CodeSource} within the 945 * {@code ProtectionDomain} of the class. Any classes added to that 946 * package must contain the same set of certificates or a 947 * {@code SecurityException} will be thrown. Note that if 948 * {@code name} is {@code null}, this check is not performed. 949 * You should always pass in the <a href="#binary-name">binary name</a> of the 950 * class you are defining as well as the bytes. This ensures that the 951 * class you are defining is indeed the class you think it is. 952 * 953 * <p> If the specified {@code name} begins with "{@code java.}", it can 954 * only be defined by the {@linkplain #getPlatformClassLoader() 955 * platform class loader} or its ancestors; otherwise {@code SecurityException} 956 * will be thrown. If {@code name} is not {@code null}, it must be equal to 957 * the <a href="#binary-name">binary name</a> of the class 958 * specified by the byte array {@code b}, otherwise a {@link 959 * NoClassDefFoundError NoClassDefFoundError} will be thrown. 960 * 961 * <p> This method defines a package in this class loader corresponding to the 962 * package of the {@code Class} (if such a package has not already been defined 963 * in this class loader). The name of the defined package is derived from 964 * the <a href="#binary-name">binary name</a> of the class specified by 965 * the byte array {@code b}. 966 * Other properties of the defined package are as specified by {@link Package}. 967 * 968 * @param name 969 * The expected <a href="#binary-name">binary name</a> of the class, or 970 * {@code null} if not known 971 * 972 * @param b 973 * The bytes that make up the class data. The bytes in positions 974 * {@code off} through {@code off+len-1} should have the format 975 * of a valid class file as defined by 976 * <cite>The Java™ Virtual Machine Specification</cite>. 977 * 978 * @param off 979 * The start offset in {@code b} of the class data 980 * 981 * @param len 982 * The length of the class data 983 * 984 * @param protectionDomain 985 * The {@code ProtectionDomain} of the class 986 * 987 * @return The {@code Class} object created from the data, 988 * and {@code ProtectionDomain}. 989 * 990 * @throws ClassFormatError 991 * If the data did not contain a valid class 992 * 993 * @throws NoClassDefFoundError 994 * If {@code name} is not {@code null} and not equal to the 995 * <a href="#binary-name">binary name</a> of the class specified by {@code b} 996 * 997 * @throws IndexOutOfBoundsException 998 * If either {@code off} or {@code len} is negative, or if 999 * {@code off+len} is greater than {@code b.length}. 1000 * 1001 * @throws SecurityException 1002 * If an attempt is made to add this class to a package that 1003 * contains classes that were signed by a different set of 1004 * certificates than this class, or if {@code name} begins with 1005 * "{@code java.}" and this class loader is not the platform 1006 * class loader or its ancestor. 1007 * 1008 * @revised 9 1009 * @spec JPMS 1010 */ 1011 protected final Class<?> defineClass(String name, byte[] b, int off, int len, 1012 ProtectionDomain protectionDomain) 1013 throws ClassFormatError 1014 { 1015 protectionDomain = preDefineClass(name, protectionDomain); 1016 String source = defineClassSourceLocation(protectionDomain); 1017 Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source); 1018 postDefineClass(c, protectionDomain); 1019 return c; 1020 } 1021 1022 /** 1023 * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance 1024 * of class {@code Class}, with the given {@code ProtectionDomain}. 1025 * If the given {@code ProtectionDomain} is {@code null}, then a default 1026 * protection domain will be assigned to the class as 1027 * specified in the documentation for {@link #defineClass(String, byte[], 1028 * int, int)}. Before the class can be used it must be resolved. 1029 * 1030 * <p>The rules about the first class defined in a package determining the 1031 * set of certificates for the package, the restrictions on class names, 1032 * and the defined package of the class 1033 * are identical to those specified in the documentation for {@link 1034 * #defineClass(String, byte[], int, int, ProtectionDomain)}. 1035 * 1036 * <p> An invocation of this method of the form 1037 * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,} 1038 * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same 1039 * result as the statements 1040 * 1041 *<p> <code> 1042 * ...<br> 1043 * byte[] temp = new byte[bBuffer.{@link 1044 * java.nio.ByteBuffer#remaining remaining}()];<br> 1045 * bBuffer.{@link java.nio.ByteBuffer#get(byte[]) 1046 * get}(temp);<br> 1047 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain) 1048 * cl.defineClass}(name, temp, 0, 1049 * temp.length, pd);<br> 1050 * </code></p> 1051 * 1052 * @param name 1053 * The expected <a href="#binary-name">binary name</a>. of the class, or 1054 * {@code null} if not known 1055 * 1056 * @param b 1057 * The bytes that make up the class data. The bytes from positions 1058 * {@code b.position()} through {@code b.position() + b.limit() -1 1059 * } should have the format of a valid class file as defined by 1060 * <cite>The Java™ Virtual Machine Specification</cite>. 1061 * 1062 * @param protectionDomain 1063 * The {@code ProtectionDomain} of the class, or {@code null}. 1064 * 1065 * @return The {@code Class} object created from the data, 1066 * and {@code ProtectionDomain}. 1067 * 1068 * @throws ClassFormatError 1069 * If the data did not contain a valid class. 1070 * 1071 * @throws NoClassDefFoundError 1072 * If {@code name} is not {@code null} and not equal to the 1073 * <a href="#binary-name">binary name</a> of the class specified by {@code b} 1074 * 1075 * @throws SecurityException 1076 * If an attempt is made to add this class to a package that 1077 * contains classes that were signed by a different set of 1078 * certificates than this class, or if {@code name} begins with 1079 * "{@code java.}". 1080 * 1081 * @see #defineClass(String, byte[], int, int, ProtectionDomain) 1082 * 1083 * @since 1.5 1084 * @revised 9 1085 * @spec JPMS 1086 */ 1087 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b, 1088 ProtectionDomain protectionDomain) 1089 throws ClassFormatError 1090 { 1091 int len = b.remaining(); 1092 1093 // Use byte[] if not a direct ByteBuffer: 1094 if (!b.isDirect()) { 1095 if (b.hasArray()) { 1096 return defineClass(name, b.array(), 1097 b.position() + b.arrayOffset(), len, 1098 protectionDomain); 1099 } else { 1100 // no array, or read-only array 1101 byte[] tb = new byte[len]; 1102 b.get(tb); // get bytes out of byte buffer. 1103 return defineClass(name, tb, 0, len, protectionDomain); 1104 } 1105 } 1106 1107 protectionDomain = preDefineClass(name, protectionDomain); 1108 String source = defineClassSourceLocation(protectionDomain); 1109 Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source); 1110 postDefineClass(c, protectionDomain); 1111 return c; 1112 } 1113 1114 static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len, 1115 ProtectionDomain pd, String source); 1116 1117 static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b, 1118 int off, int len, ProtectionDomain pd, 1119 String source); 1120 1121 // true if the name is null or has the potential to be a valid binary name 1122 private boolean checkName(String name) { 1123 if ((name == null) || (name.isEmpty())) 1124 return true; 1125 if ((name.indexOf('/') != -1) || (name.charAt(0) == '[')) 1126 return false; 1127 return true; 1128 } 1129 1130 private void checkCerts(String name, CodeSource cs) { 1131 int i = name.lastIndexOf('.'); 1132 String pname = (i == -1) ? "" : name.substring(0, i); 1133 1134 Certificate[] certs = null; 1135 if (cs != null) { 1136 certs = cs.getCertificates(); 1137 } 1138 Certificate[] pcerts = null; 1139 if (parallelLockMap == null) { 1140 synchronized (this) { 1141 pcerts = package2certs.get(pname); 1142 if (pcerts == null) { 1143 package2certs.put(pname, (certs == null? nocerts:certs)); 1144 } 1145 } 1146 } else { 1147 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs). 1148 putIfAbsent(pname, (certs == null? nocerts:certs)); 1149 } 1150 if (pcerts != null && !compareCerts(pcerts, certs)) { 1151 throw new SecurityException("class \"" + name 1152 + "\"'s signer information does not match signer information" 1153 + " of other classes in the same package"); 1154 } 1155 } 1156 1157 /** 1158 * check to make sure the certs for the new class (certs) are the same as 1159 * the certs for the first class inserted in the package (pcerts) 1160 */ 1161 private boolean compareCerts(Certificate[] pcerts, 1162 Certificate[] certs) 1163 { 1164 // certs can be null, indicating no certs. 1165 if ((certs == null) || (certs.length == 0)) { 1166 return pcerts.length == 0; 1167 } 1168 1169 // the length must be the same at this point 1170 if (certs.length != pcerts.length) 1171 return false; 1172 1173 // go through and make sure all the certs in one array 1174 // are in the other and vice-versa. 1175 boolean match; 1176 for (Certificate cert : certs) { 1177 match = false; 1178 for (Certificate pcert : pcerts) { 1179 if (cert.equals(pcert)) { 1180 match = true; 1181 break; 1182 } 1183 } 1184 if (!match) return false; 1185 } 1186 1187 // now do the same for pcerts 1188 for (Certificate pcert : pcerts) { 1189 match = false; 1190 for (Certificate cert : certs) { 1191 if (pcert.equals(cert)) { 1192 match = true; 1193 break; 1194 } 1195 } 1196 if (!match) return false; 1197 } 1198 1199 return true; 1200 } 1201 1202 /** 1203 * Links the specified class. This (misleadingly named) method may be 1204 * used by a class loader to link a class. If the class {@code c} has 1205 * already been linked, then this method simply returns. Otherwise, the 1206 * class is linked as described in the "Execution" chapter of 1207 * <cite>The Java™ Language Specification</cite>. 1208 * 1209 * @param c 1210 * The class to link 1211 * 1212 * @throws NullPointerException 1213 * If {@code c} is {@code null}. 1214 * 1215 * @see #defineClass(String, byte[], int, int) 1216 */ 1217 protected final void resolveClass(Class<?> c) { 1218 if (c == null) { 1219 throw new NullPointerException(); 1220 } 1221 } 1222 1223 /** 1224 * Finds a class with the specified <a href="#binary-name">binary name</a>, 1225 * loading it if necessary. 1226 * 1227 * <p> This method loads the class through the system class loader (see 1228 * {@link #getSystemClassLoader()}). The {@code Class} object returned 1229 * might have more than one {@code ClassLoader} associated with it. 1230 * Subclasses of {@code ClassLoader} need not usually invoke this method, 1231 * because most class loaders need to override just {@link 1232 * #findClass(String)}. </p> 1233 * 1234 * @param name 1235 * The <a href="#binary-name">binary name</a> of the class 1236 * 1237 * @return The {@code Class} object for the specified {@code name} 1238 * 1239 * @throws ClassNotFoundException 1240 * If the class could not be found 1241 * 1242 * @see #ClassLoader(ClassLoader) 1243 * @see #getParent() 1244 */ 1245 protected final Class<?> findSystemClass(String name) 1246 throws ClassNotFoundException 1247 { 1248 return getSystemClassLoader().loadClass(name); 1249 } 1250 1251 /** 1252 * Returns a class loaded by the bootstrap class loader; 1253 * or return null if not found. 1254 */ 1255 Class<?> findBootstrapClassOrNull(String name) { 1256 if (!checkName(name)) return null; 1257 1258 return findBootstrapClass(name); 1259 } 1260 1261 // return null if not found 1262 private native Class<?> findBootstrapClass(String name); 1263 1264 /** 1265 * Returns the class with the given <a href="#binary-name">binary name</a> if this 1266 * loader has been recorded by the Java virtual machine as an initiating 1267 * loader of a class with that <a href="#binary-name">binary name</a>. Otherwise 1268 * {@code null} is returned. 1269 * 1270 * @param name 1271 * The <a href="#binary-name">binary name</a> of the class 1272 * 1273 * @return The {@code Class} object, or {@code null} if the class has 1274 * not been loaded 1275 * 1276 * @since 1.1 1277 */ 1278 protected final Class<?> findLoadedClass(String name) { 1279 if (!checkName(name)) 1280 return null; 1281 return findLoadedClass0(name); 1282 } 1283 1284 private final native Class<?> findLoadedClass0(String name); 1285 1286 /** 1287 * Sets the signers of a class. This should be invoked after defining a 1288 * class. 1289 * 1290 * @param c 1291 * The {@code Class} object 1292 * 1293 * @param signers 1294 * The signers for the class 1295 * 1296 * @since 1.1 1297 */ 1298 protected final void setSigners(Class<?> c, Object[] signers) { 1299 c.setSigners(signers); 1300 } 1301 1302 1303 // -- Resources -- 1304 1305 /** 1306 * Returns a URL to a resource in a module defined to this class loader. 1307 * Class loader implementations that support loading from modules 1308 * should override this method. 1309 * 1310 * @apiNote This method is the basis for the {@link 1311 * Class#getResource Class.getResource}, {@link Class#getResourceAsStream 1312 * Class.getResourceAsStream}, and {@link Module#getResourceAsStream 1313 * Module.getResourceAsStream} methods. It is not subject to the rules for 1314 * encapsulation specified by {@code Module.getResourceAsStream}. 1315 * 1316 * @implSpec The default implementation attempts to find the resource by 1317 * invoking {@link #findResource(String)} when the {@code moduleName} is 1318 * {@code null}. It otherwise returns {@code null}. 1319 * 1320 * @param moduleName 1321 * The module name; or {@code null} to find a resource in the 1322 * {@linkplain #getUnnamedModule() unnamed module} for this 1323 * class loader 1324 * @param name 1325 * The resource name 1326 * 1327 * @return A URL to the resource; {@code null} if the resource could not be 1328 * found, a URL could not be constructed to locate the resource, 1329 * access to the resource is denied by the security manager, or 1330 * there isn't a module of the given name defined to the class 1331 * loader. 1332 * 1333 * @throws IOException 1334 * If I/O errors occur 1335 * 1336 * @see java.lang.module.ModuleReader#find(String) 1337 * @since 9 1338 * @spec JPMS 1339 */ 1340 protected URL findResource(String moduleName, String name) throws IOException { 1341 if (moduleName == null) { 1342 return findResource(name); 1343 } else { 1344 return null; 1345 } 1346 } 1347 1348 /** 1349 * Finds the resource with the given name. A resource is some data 1350 * (images, audio, text, etc) that can be accessed by class code in a way 1351 * that is independent of the location of the code. 1352 * 1353 * <p> The name of a resource is a '{@code /}'-separated path name that 1354 * identifies the resource. </p> 1355 * 1356 * <p> Resources in named modules are subject to the encapsulation rules 1357 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1358 * Additionally, and except for the special case where the resource has a 1359 * name ending with "{@code .class}", this method will only find resources in 1360 * packages of named modules when the package is {@link Module#isOpen(String) 1361 * opened} unconditionally (even if the caller of this method is in the 1362 * same module as the resource). </p> 1363 * 1364 * @implSpec The default implementation will first search the parent class 1365 * loader for the resource; if the parent is {@code null} the path of the 1366 * class loader built into the virtual machine is searched. If not found, 1367 * this method will invoke {@link #findResource(String)} to find the resource. 1368 * 1369 * @apiNote Where several modules are defined to the same class loader, 1370 * and where more than one module contains a resource with the given name, 1371 * then the ordering that modules are searched is not specified and may be 1372 * very unpredictable. 1373 * When overriding this method it is recommended that an implementation 1374 * ensures that any delegation is consistent with the {@link 1375 * #getResources(java.lang.String) getResources(String)} method. 1376 * 1377 * @param name 1378 * The resource name 1379 * 1380 * @return {@code URL} object for reading the resource; {@code null} if 1381 * the resource could not be found, a {@code URL} could not be 1382 * constructed to locate the resource, the resource is in a package 1383 * that is not opened unconditionally, or access to the resource is 1384 * denied by the security manager. 1385 * 1386 * @throws NullPointerException If {@code name} is {@code null} 1387 * 1388 * @since 1.1 1389 * @revised 9 1390 * @spec JPMS 1391 */ 1392 public URL getResource(String name) { 1393 Objects.requireNonNull(name); 1394 URL url; 1395 if (parent != null) { 1396 url = parent.getResource(name); 1397 } else { 1398 url = BootLoader.findResource(name); 1399 } 1400 if (url == null) { 1401 url = findResource(name); 1402 } 1403 return url; 1404 } 1405 1406 /** 1407 * Finds all the resources with the given name. A resource is some data 1408 * (images, audio, text, etc) that can be accessed by class code in a way 1409 * that is independent of the location of the code. 1410 * 1411 * <p> The name of a resource is a {@code /}-separated path name that 1412 * identifies the resource. </p> 1413 * 1414 * <p> Resources in named modules are subject to the encapsulation rules 1415 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1416 * Additionally, and except for the special case where the resource has a 1417 * name ending with "{@code .class}", this method will only find resources in 1418 * packages of named modules when the package is {@link Module#isOpen(String) 1419 * opened} unconditionally (even if the caller of this method is in the 1420 * same module as the resource). </p> 1421 * 1422 * @implSpec The default implementation will first search the parent class 1423 * loader for the resource; if the parent is {@code null} the path of the 1424 * class loader built into the virtual machine is searched. It then 1425 * invokes {@link #findResources(String)} to find the resources with the 1426 * name in this class loader. It returns an enumeration whose elements 1427 * are the URLs found by searching the parent class loader followed by 1428 * the elements found with {@code findResources}. 1429 * 1430 * @apiNote Where several modules are defined to the same class loader, 1431 * and where more than one module contains a resource with the given name, 1432 * then the ordering is not specified and may be very unpredictable. 1433 * When overriding this method it is recommended that an 1434 * implementation ensures that any delegation is consistent with the {@link 1435 * #getResource(java.lang.String) getResource(String)} method. This should 1436 * ensure that the first element returned by the Enumeration's 1437 * {@code nextElement} method is the same resource that the 1438 * {@code getResource(String)} method would return. 1439 * 1440 * @param name 1441 * The resource name 1442 * 1443 * @return An enumeration of {@link java.net.URL URL} objects for the 1444 * resource. If no resources could be found, the enumeration will 1445 * be empty. Resources for which a {@code URL} cannot be 1446 * constructed, are in a package that is not opened 1447 * unconditionally, or access to the resource is denied by the 1448 * security manager, are not returned in the enumeration. 1449 * 1450 * @throws IOException 1451 * If I/O errors occur 1452 * @throws NullPointerException If {@code name} is {@code null} 1453 * 1454 * @since 1.2 1455 * @revised 9 1456 * @spec JPMS 1457 */ 1458 public Enumeration<URL> getResources(String name) throws IOException { 1459 Objects.requireNonNull(name); 1460 @SuppressWarnings("unchecked") 1461 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2]; 1462 if (parent != null) { 1463 tmp[0] = parent.getResources(name); 1464 } else { 1465 tmp[0] = BootLoader.findResources(name); 1466 } 1467 tmp[1] = findResources(name); 1468 1469 return new CompoundEnumeration<>(tmp); 1470 } 1471 1472 /** 1473 * Returns a stream whose elements are the URLs of all the resources with 1474 * the given name. A resource is some data (images, audio, text, etc) that 1475 * can be accessed by class code in a way that is independent of the 1476 * location of the code. 1477 * 1478 * <p> The name of a resource is a {@code /}-separated path name that 1479 * identifies the resource. 1480 * 1481 * <p> The resources will be located when the returned stream is evaluated. 1482 * If the evaluation results in an {@code IOException} then the I/O 1483 * exception is wrapped in an {@link UncheckedIOException} that is then 1484 * thrown. 1485 * 1486 * <p> Resources in named modules are subject to the encapsulation rules 1487 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1488 * Additionally, and except for the special case where the resource has a 1489 * name ending with "{@code .class}", this method will only find resources in 1490 * packages of named modules when the package is {@link Module#isOpen(String) 1491 * opened} unconditionally (even if the caller of this method is in the 1492 * same module as the resource). </p> 1493 * 1494 * @implSpec The default implementation invokes {@link #getResources(String) 1495 * getResources} to find all the resources with the given name and returns 1496 * a stream with the elements in the enumeration as the source. 1497 * 1498 * @apiNote When overriding this method it is recommended that an 1499 * implementation ensures that any delegation is consistent with the {@link 1500 * #getResource(java.lang.String) getResource(String)} method. This should 1501 * ensure that the first element returned by the stream is the same 1502 * resource that the {@code getResource(String)} method would return. 1503 * 1504 * @param name 1505 * The resource name 1506 * 1507 * @return A stream of resource {@link java.net.URL URL} objects. If no 1508 * resources could be found, the stream will be empty. Resources 1509 * for which a {@code URL} cannot be constructed, are in a package 1510 * that is not opened unconditionally, or access to the resource 1511 * is denied by the security manager, will not be in the stream. 1512 * 1513 * @throws NullPointerException If {@code name} is {@code null} 1514 * 1515 * @since 9 1516 */ 1517 public Stream<URL> resources(String name) { 1518 Objects.requireNonNull(name); 1519 int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE; 1520 Supplier<Spliterator<URL>> si = () -> { 1521 try { 1522 return Spliterators.spliteratorUnknownSize( 1523 getResources(name).asIterator(), characteristics); 1524 } catch (IOException e) { 1525 throw new UncheckedIOException(e); 1526 } 1527 }; 1528 return StreamSupport.stream(si, characteristics, false); 1529 } 1530 1531 /** 1532 * Finds the resource with the given name. Class loader implementations 1533 * should override this method. 1534 * 1535 * <p> For resources in named modules then the method must implement the 1536 * rules for encapsulation specified in the {@code Module} {@link 1537 * Module#getResourceAsStream getResourceAsStream} method. Additionally, 1538 * it must not find non-"{@code .class}" resources in packages of named 1539 * modules unless the package is {@link Module#isOpen(String) opened} 1540 * unconditionally. </p> 1541 * 1542 * @implSpec The default implementation returns {@code null}. 1543 * 1544 * @param name 1545 * The resource name 1546 * 1547 * @return {@code URL} object for reading the resource; {@code null} if 1548 * the resource could not be found, a {@code URL} could not be 1549 * constructed to locate the resource, the resource is in a package 1550 * that is not opened unconditionally, or access to the resource is 1551 * denied by the security manager. 1552 * 1553 * @since 1.2 1554 * @revised 9 1555 * @spec JPMS 1556 */ 1557 protected URL findResource(String name) { 1558 return null; 1559 } 1560 1561 /** 1562 * Returns an enumeration of {@link java.net.URL URL} objects 1563 * representing all the resources with the given name. Class loader 1564 * implementations should override this method. 1565 * 1566 * <p> For resources in named modules then the method must implement the 1567 * rules for encapsulation specified in the {@code Module} {@link 1568 * Module#getResourceAsStream getResourceAsStream} method. Additionally, 1569 * it must not find non-"{@code .class}" resources in packages of named 1570 * modules unless the package is {@link Module#isOpen(String) opened} 1571 * unconditionally. </p> 1572 * 1573 * @implSpec The default implementation returns an enumeration that 1574 * contains no elements. 1575 * 1576 * @param name 1577 * The resource name 1578 * 1579 * @return An enumeration of {@link java.net.URL URL} objects for 1580 * the resource. If no resources could be found, the enumeration 1581 * will be empty. Resources for which a {@code URL} cannot be 1582 * constructed, are in a package that is not opened unconditionally, 1583 * or access to the resource is denied by the security manager, 1584 * are not returned in the enumeration. 1585 * 1586 * @throws IOException 1587 * If I/O errors occur 1588 * 1589 * @since 1.2 1590 * @revised 9 1591 * @spec JPMS 1592 */ 1593 protected Enumeration<URL> findResources(String name) throws IOException { 1594 return Collections.emptyEnumeration(); 1595 } 1596 1597 /** 1598 * Registers the caller as 1599 * {@linkplain #isRegisteredAsParallelCapable() parallel capable}. 1600 * The registration succeeds if and only if all of the following 1601 * conditions are met: 1602 * <ol> 1603 * <li> no instance of the caller has been created</li> 1604 * <li> all of the super classes (except class Object) of the caller are 1605 * registered as parallel capable</li> 1606 * </ol> 1607 * <p>Note that once a class loader is registered as parallel capable, there 1608 * is no way to change it back.</p> 1609 * 1610 * @return {@code true} if the caller is successfully registered as 1611 * parallel capable and {@code false} if otherwise. 1612 * 1613 * @see #isRegisteredAsParallelCapable() 1614 * 1615 * @since 1.7 1616 */ 1617 @CallerSensitive 1618 protected static boolean registerAsParallelCapable() { 1619 Class<? extends ClassLoader> callerClass = 1620 Reflection.getCallerClass().asSubclass(ClassLoader.class); 1621 return ParallelLoaders.register(callerClass); 1622 } 1623 1624 /** 1625 * Returns {@code true} if this class loader is registered as 1626 * {@linkplain #registerAsParallelCapable parallel capable}, otherwise 1627 * {@code false}. 1628 * 1629 * @return {@code true} if this class loader is parallel capable, 1630 * otherwise {@code false}. 1631 * 1632 * @see #registerAsParallelCapable() 1633 * 1634 * @since 9 1635 */ 1636 public final boolean isRegisteredAsParallelCapable() { 1637 return ParallelLoaders.isRegistered(this.getClass()); 1638 } 1639 1640 /** 1641 * Find a resource of the specified name from the search path used to load 1642 * classes. This method locates the resource through the system class 1643 * loader (see {@link #getSystemClassLoader()}). 1644 * 1645 * <p> Resources in named modules are subject to the encapsulation rules 1646 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1647 * Additionally, and except for the special case where the resource has a 1648 * name ending with "{@code .class}", this method will only find resources in 1649 * packages of named modules when the package is {@link Module#isOpen(String) 1650 * opened} unconditionally. </p> 1651 * 1652 * @param name 1653 * The resource name 1654 * 1655 * @return A {@link java.net.URL URL} to the resource; {@code 1656 * null} if the resource could not be found, a URL could not be 1657 * constructed to locate the resource, the resource is in a package 1658 * that is not opened unconditionally or access to the resource is 1659 * denied by the security manager. 1660 * 1661 * @since 1.1 1662 * @revised 9 1663 * @spec JPMS 1664 */ 1665 public static URL getSystemResource(String name) { 1666 return getSystemClassLoader().getResource(name); 1667 } 1668 1669 /** 1670 * Finds all resources of the specified name from the search path used to 1671 * load classes. The resources thus found are returned as an 1672 * {@link java.util.Enumeration Enumeration} of {@link 1673 * java.net.URL URL} objects. 1674 * 1675 * <p> The search order is described in the documentation for {@link 1676 * #getSystemResource(String)}. </p> 1677 * 1678 * <p> Resources in named modules are subject to the encapsulation rules 1679 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1680 * Additionally, and except for the special case where the resource has a 1681 * name ending with "{@code .class}", this method will only find resources in 1682 * packages of named modules when the package is {@link Module#isOpen(String) 1683 * opened} unconditionally. </p> 1684 * 1685 * @param name 1686 * The resource name 1687 * 1688 * @return An enumeration of {@link java.net.URL URL} objects for 1689 * the resource. If no resources could be found, the enumeration 1690 * will be empty. Resources for which a {@code URL} cannot be 1691 * constructed, are in a package that is not opened unconditionally, 1692 * or access to the resource is denied by the security manager, 1693 * are not returned in the enumeration. 1694 * 1695 * @throws IOException 1696 * If I/O errors occur 1697 * 1698 * @since 1.2 1699 * @revised 9 1700 * @spec JPMS 1701 */ 1702 public static Enumeration<URL> getSystemResources(String name) 1703 throws IOException 1704 { 1705 return getSystemClassLoader().getResources(name); 1706 } 1707 1708 /** 1709 * Returns an input stream for reading the specified resource. 1710 * 1711 * <p> The search order is described in the documentation for {@link 1712 * #getResource(String)}. </p> 1713 * 1714 * <p> Resources in named modules are subject to the encapsulation rules 1715 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1716 * Additionally, and except for the special case where the resource has a 1717 * name ending with "{@code .class}", this method will only find resources in 1718 * packages of named modules when the package is {@link Module#isOpen(String) 1719 * opened} unconditionally. </p> 1720 * 1721 * @param name 1722 * The resource name 1723 * 1724 * @return An input stream for reading the resource; {@code null} if the 1725 * resource could not be found, the resource is in a package that 1726 * is not opened unconditionally, or access to the resource is 1727 * denied by the security manager. 1728 * 1729 * @throws NullPointerException If {@code name} is {@code null} 1730 * 1731 * @since 1.1 1732 * @revised 9 1733 * @spec JPMS 1734 */ 1735 public InputStream getResourceAsStream(String name) { 1736 Objects.requireNonNull(name); 1737 URL url = getResource(name); 1738 try { 1739 return url != null ? url.openStream() : null; 1740 } catch (IOException e) { 1741 return null; 1742 } 1743 } 1744 1745 /** 1746 * Open for reading, a resource of the specified name from the search path 1747 * used to load classes. This method locates the resource through the 1748 * system class loader (see {@link #getSystemClassLoader()}). 1749 * 1750 * <p> Resources in named modules are subject to the encapsulation rules 1751 * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. 1752 * Additionally, and except for the special case where the resource has a 1753 * name ending with "{@code .class}", this method will only find resources in 1754 * packages of named modules when the package is {@link Module#isOpen(String) 1755 * opened} unconditionally. </p> 1756 * 1757 * @param name 1758 * The resource name 1759 * 1760 * @return An input stream for reading the resource; {@code null} if the 1761 * resource could not be found, the resource is in a package that 1762 * is not opened unconditionally, or access to the resource is 1763 * denied by the security manager. 1764 * 1765 * @since 1.1 1766 * @revised 9 1767 * @spec JPMS 1768 */ 1769 public static InputStream getSystemResourceAsStream(String name) { 1770 URL url = getSystemResource(name); 1771 try { 1772 return url != null ? url.openStream() : null; 1773 } catch (IOException e) { 1774 return null; 1775 } 1776 } 1777 1778 1779 // -- Hierarchy -- 1780 1781 /** 1782 * Returns the parent class loader for delegation. Some implementations may 1783 * use {@code null} to represent the bootstrap class loader. This method 1784 * will return {@code null} in such implementations if this class loader's 1785 * parent is the bootstrap class loader. 1786 * 1787 * @return The parent {@code ClassLoader} 1788 * 1789 * @throws SecurityException 1790 * If a security manager is present, and the caller's class loader 1791 * is not {@code null} and is not an ancestor of this class loader, 1792 * and the caller does not have the 1793 * {@link RuntimePermission}{@code ("getClassLoader")} 1794 * 1795 * @since 1.2 1796 */ 1797 @CallerSensitive 1798 public final ClassLoader getParent() { 1799 if (parent == null) 1800 return null; 1801 SecurityManager sm = System.getSecurityManager(); 1802 if (sm != null) { 1803 // Check access to the parent class loader 1804 // If the caller's class loader is same as this class loader, 1805 // permission check is performed. 1806 checkClassLoaderPermission(parent, Reflection.getCallerClass()); 1807 } 1808 return parent; 1809 } 1810 1811 /** 1812 * Returns the unnamed {@code Module} for this class loader. 1813 * 1814 * @return The unnamed Module for this class loader 1815 * 1816 * @see Module#isNamed() 1817 * @since 9 1818 * @spec JPMS 1819 */ 1820 public final Module getUnnamedModule() { 1821 return unnamedModule; 1822 } 1823 1824 /** 1825 * Returns the platform class loader. All 1826 * <a href="#builtinLoaders">platform classes</a> are visible to 1827 * the platform class loader. 1828 * 1829 * @implNote The name of the builtin platform class loader is 1830 * {@code "platform"}. 1831 * 1832 * @return The platform {@code ClassLoader}. 1833 * 1834 * @throws SecurityException 1835 * If a security manager is present, and the caller's class loader is 1836 * not {@code null}, and the caller's class loader is not the same 1837 * as or an ancestor of the platform class loader, 1838 * and the caller does not have the 1839 * {@link RuntimePermission}{@code ("getClassLoader")} 1840 * 1841 * @since 9 1842 * @spec JPMS 1843 */ 1844 @CallerSensitive 1845 public static ClassLoader getPlatformClassLoader() { 1846 SecurityManager sm = System.getSecurityManager(); 1847 ClassLoader loader = getBuiltinPlatformClassLoader(); 1848 if (sm != null) { 1849 checkClassLoaderPermission(loader, Reflection.getCallerClass()); 1850 } 1851 return loader; 1852 } 1853 1854 /** 1855 * Returns the system class loader. This is the default 1856 * delegation parent for new {@code ClassLoader} instances, and is 1857 * typically the class loader used to start the application. 1858 * 1859 * <p> This method is first invoked early in the runtime's startup 1860 * sequence, at which point it creates the system class loader. This 1861 * class loader will be the context class loader for the main application 1862 * thread (for example, the thread that invokes the {@code main} method of 1863 * the main class). 1864 * 1865 * <p> The default system class loader is an implementation-dependent 1866 * instance of this class. 1867 * 1868 * <p> If the system property "{@systemProperty java.system.class.loader}" 1869 * is defined when this method is first invoked then the value of that 1870 * property is taken to be the name of a class that will be returned as the 1871 * system class loader. The class is loaded using the default system class 1872 * loader and must define a public constructor that takes a single parameter 1873 * of type {@code ClassLoader} which is used as the delegation parent. An 1874 * instance is then created using this constructor with the default system 1875 * class loader as the parameter. The resulting class loader is defined 1876 * to be the system class loader. During construction, the class loader 1877 * should take great care to avoid calling {@code getSystemClassLoader()}. 1878 * If circular initialization of the system class loader is detected then 1879 * an {@code IllegalStateException} is thrown. 1880 * 1881 * @implNote The system property to override the system class loader is not 1882 * examined until the VM is almost fully initialized. Code that executes 1883 * this method during startup should take care not to cache the return 1884 * value until the system is fully initialized. 1885 * 1886 * <p> The name of the built-in system class loader is {@code "app"}. 1887 * The system property "{@code java.class.path}" is read during early 1888 * initialization of the VM to determine the class path. 1889 * An empty value of "{@code java.class.path}" property is interpreted 1890 * differently depending on whether the initial module (the module 1891 * containing the main class) is named or unnamed: 1892 * If named, the built-in system class loader will have no class path and 1893 * will search for classes and resources using the application module path; 1894 * otherwise, if unnamed, it will set the class path to the current 1895 * working directory. 1896 * 1897 * <p> JAR files on the class path may contain a {@code Class-Path} manifest 1898 * attribute to specify dependent JAR files to be included in the class path. 1899 * {@code Class-Path} entries must meet certain conditions for validity (see 1900 * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute"> 1901 * JAR File Specification</a> for details). Invalid {@code Class-Path} 1902 * entries are ignored. For debugging purposes, ignored entries can be 1903 * printed to the console if the 1904 * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system 1905 * property is set to {@code true}. 1906 * 1907 * @return The system {@code ClassLoader} 1908 * 1909 * @throws SecurityException 1910 * If a security manager is present, and the caller's class loader 1911 * is not {@code null} and is not the same as or an ancestor of the 1912 * system class loader, and the caller does not have the 1913 * {@link RuntimePermission}{@code ("getClassLoader")} 1914 * 1915 * @throws IllegalStateException 1916 * If invoked recursively during the construction of the class 1917 * loader specified by the "{@code java.system.class.loader}" 1918 * property. 1919 * 1920 * @throws Error 1921 * If the system property "{@code java.system.class.loader}" 1922 * is defined but the named class could not be loaded, the 1923 * provider class does not define the required constructor, or an 1924 * exception is thrown by that constructor when it is invoked. The 1925 * underlying cause of the error can be retrieved via the 1926 * {@link Throwable#getCause()} method. 1927 * 1928 * @revised 1.4 1929 * @revised 9 1930 * @spec JPMS 1931 */ 1932 @CallerSensitive 1933 public static ClassLoader getSystemClassLoader() { 1934 switch (VM.initLevel()) { 1935 case 0: 1936 case 1: 1937 case 2: 1938 // the system class loader is the built-in app class loader during startup 1939 return getBuiltinAppClassLoader(); 1940 case 3: 1941 String msg = "getSystemClassLoader cannot be called during the system class loader instantiation"; 1942 throw new IllegalStateException(msg); 1943 default: 1944 // system fully initialized 1945 assert VM.isBooted() && scl != null; 1946 SecurityManager sm = System.getSecurityManager(); 1947 if (sm != null) { 1948 checkClassLoaderPermission(scl, Reflection.getCallerClass()); 1949 } 1950 return scl; 1951 } 1952 } 1953 1954 static ClassLoader getBuiltinPlatformClassLoader() { 1955 return ClassLoaders.platformClassLoader(); 1956 } 1957 1958 static ClassLoader getBuiltinAppClassLoader() { 1959 return ClassLoaders.appClassLoader(); 1960 } 1961 1962 /* 1963 * Initialize the system class loader that may be a custom class on the 1964 * application class path or application module path. 1965 * 1966 * @see java.lang.System#initPhase3 1967 */ 1968 static synchronized ClassLoader initSystemClassLoader() { 1969 if (VM.initLevel() != 3) { 1970 throw new InternalError("system class loader cannot be set at initLevel " + 1971 VM.initLevel()); 1972 } 1973 1974 // detect recursive initialization 1975 if (scl != null) { 1976 throw new IllegalStateException("recursive invocation"); 1977 } 1978 1979 ClassLoader builtinLoader = getBuiltinAppClassLoader(); 1980 1981 // All are privileged frames. No need to call doPrivileged. 1982 String cn = System.getProperty("java.system.class.loader"); 1983 if (cn != null) { 1984 try { 1985 // custom class loader is only supported to be loaded from unnamed module 1986 Constructor<?> ctor = Class.forName(cn, false, builtinLoader) 1987 .getDeclaredConstructor(ClassLoader.class); 1988 scl = (ClassLoader) ctor.newInstance(builtinLoader); 1989 } catch (Exception e) { 1990 Throwable cause = e; 1991 if (e instanceof InvocationTargetException) { 1992 cause = e.getCause(); 1993 if (cause instanceof Error) { 1994 throw (Error) cause; 1995 } 1996 } 1997 if (cause instanceof RuntimeException) { 1998 throw (RuntimeException) cause; 1999 } 2000 throw new Error(cause.getMessage(), cause); 2001 } 2002 } else { 2003 scl = builtinLoader; 2004 } 2005 return scl; 2006 } 2007 2008 /* 2009 * Initialize default paths for native libraries search. 2010 * Must be done early as JDK may load libraries during bootstrap. 2011 * 2012 * @see java.lang.System#initPhase1 2013 */ 2014 static void initLibraryPaths() { 2015 usr_paths = initializePath("java.library.path"); 2016 sys_paths = initializePath("sun.boot.library.path"); 2017 } 2018 2019 // Returns true if the specified class loader can be found in this class 2020 // loader's delegation chain. 2021 boolean isAncestor(ClassLoader cl) { 2022 ClassLoader acl = this; 2023 do { 2024 acl = acl.parent; 2025 if (cl == acl) { 2026 return true; 2027 } 2028 } while (acl != null); 2029 return false; 2030 } 2031 2032 // Tests if class loader access requires "getClassLoader" permission 2033 // check. A class loader 'from' can access class loader 'to' if 2034 // class loader 'from' is same as class loader 'to' or an ancestor 2035 // of 'to'. The class loader in a system domain can access 2036 // any class loader. 2037 private static boolean needsClassLoaderPermissionCheck(ClassLoader from, 2038 ClassLoader to) 2039 { 2040 if (from == to) 2041 return false; 2042 2043 if (from == null) 2044 return false; 2045 2046 return !to.isAncestor(from); 2047 } 2048 2049 // Returns the class's class loader, or null if none. 2050 static ClassLoader getClassLoader(Class<?> caller) { 2051 // This can be null if the VM is requesting it 2052 if (caller == null) { 2053 return null; 2054 } 2055 // Circumvent security check since this is package-private 2056 return caller.getClassLoader0(); 2057 } 2058 2059 /* 2060 * Checks RuntimePermission("getClassLoader") permission 2061 * if caller's class loader is not null and caller's class loader 2062 * is not the same as or an ancestor of the given cl argument. 2063 */ 2064 static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) { 2065 SecurityManager sm = System.getSecurityManager(); 2066 if (sm != null) { 2067 // caller can be null if the VM is requesting it 2068 ClassLoader ccl = getClassLoader(caller); 2069 if (needsClassLoaderPermissionCheck(ccl, cl)) { 2070 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 2071 } 2072 } 2073 } 2074 2075 // The system class loader 2076 // @GuardedBy("ClassLoader.class") 2077 private static volatile ClassLoader scl; 2078 2079 // -- Package -- 2080 2081 /** 2082 * Define a Package of the given Class object. 2083 * 2084 * If the given class represents an array type, a primitive type or void, 2085 * this method returns {@code null}. 2086 * 2087 * This method does not throw IllegalArgumentException. 2088 */ 2089 Package definePackage(Class<?> c) { 2090 if (c.isPrimitive() || c.isArray()) { 2091 return null; 2092 } 2093 2094 return definePackage(c.getPackageName(), c.getModule()); 2095 } 2096 2097 /** 2098 * Defines a Package of the given name and module 2099 * 2100 * This method does not throw IllegalArgumentException. 2101 * 2102 * @param name package name 2103 * @param m module 2104 */ 2105 Package definePackage(String name, Module m) { 2106 if (name.isEmpty() && m.isNamed()) { 2107 throw new InternalError("unnamed package in " + m); 2108 } 2109 2110 // check if Package object is already defined 2111 NamedPackage pkg = packages.get(name); 2112 if (pkg instanceof Package) 2113 return (Package)pkg; 2114 2115 return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m)); 2116 } 2117 2118 /* 2119 * Returns a Package object for the named package 2120 */ 2121 private Package toPackage(String name, NamedPackage p, Module m) { 2122 // define Package object if the named package is not yet defined 2123 if (p == null) 2124 return NamedPackage.toPackage(name, m); 2125 2126 // otherwise, replace the NamedPackage object with Package object 2127 if (p instanceof Package) 2128 return (Package)p; 2129 2130 return NamedPackage.toPackage(p.packageName(), p.module()); 2131 } 2132 2133 /** 2134 * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}. 2135 * <p> 2136 * <a href="#binary-name">Package names</a> must be unique within a class loader and 2137 * cannot be redefined or changed once created. 2138 * <p> 2139 * If a class loader wishes to define a package with specific properties, 2140 * such as version information, then the class loader should call this 2141 * {@code definePackage} method before calling {@code defineClass}. 2142 * Otherwise, the 2143 * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass} 2144 * method will define a package in this class loader corresponding to the package 2145 * of the newly defined class; the properties of this defined package are 2146 * specified by {@link Package}. 2147 * 2148 * @apiNote 2149 * A class loader that wishes to define a package for classes in a JAR 2150 * typically uses the specification and implementation titles, versions, and 2151 * vendors from the JAR's manifest. If the package is specified as 2152 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest, 2153 * the {@code URL} of the JAR file is typically used as the {@code sealBase}. 2154 * If classes of package {@code 'p'} defined by this class loader 2155 * are loaded from multiple JARs, the {@code Package} object may contain 2156 * different information depending on the first class of package {@code 'p'} 2157 * defined and which JAR's manifest is read first to explicitly define 2158 * package {@code 'p'}. 2159 * 2160 * <p> It is strongly recommended that a class loader does not call this 2161 * method to explicitly define packages in <em>named modules</em>; instead, 2162 * the package will be automatically defined when a class is {@linkplain 2163 * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}. 2164 * If it is desirable to define {@code Package} explicitly, it should ensure 2165 * that all packages in a named module are defined with the properties 2166 * specified by {@link Package}. Otherwise, some {@code Package} objects 2167 * in a named module may be for example sealed with different seal base. 2168 * 2169 * @param name 2170 * The <a href="#binary-name">package name</a> 2171 * 2172 * @param specTitle 2173 * The specification title 2174 * 2175 * @param specVersion 2176 * The specification version 2177 * 2178 * @param specVendor 2179 * The specification vendor 2180 * 2181 * @param implTitle 2182 * The implementation title 2183 * 2184 * @param implVersion 2185 * The implementation version 2186 * 2187 * @param implVendor 2188 * The implementation vendor 2189 * 2190 * @param sealBase 2191 * If not {@code null}, then this package is sealed with 2192 * respect to the given code source {@link java.net.URL URL} 2193 * object. Otherwise, the package is not sealed. 2194 * 2195 * @return The newly defined {@code Package} object 2196 * 2197 * @throws NullPointerException 2198 * if {@code name} is {@code null}. 2199 * 2200 * @throws IllegalArgumentException 2201 * if a package of the given {@code name} is already 2202 * defined by this class loader 2203 * 2204 * 2205 * @since 1.2 2206 * @revised 9 2207 * @spec JPMS 2208 * 2209 * @jvms 5.3 Creation and Loading 2210 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing"> 2211 * The JAR File Specification: Package Sealing</a> 2212 */ 2213 protected Package definePackage(String name, String specTitle, 2214 String specVersion, String specVendor, 2215 String implTitle, String implVersion, 2216 String implVendor, URL sealBase) 2217 { 2218 Objects.requireNonNull(name); 2219 2220 // definePackage is not final and may be overridden by custom class loader 2221 Package p = new Package(name, specTitle, specVersion, specVendor, 2222 implTitle, implVersion, implVendor, 2223 sealBase, this); 2224 2225 if (packages.putIfAbsent(name, p) != null) 2226 throw new IllegalArgumentException(name); 2227 2228 return p; 2229 } 2230 2231 /** 2232 * Returns a {@code Package} of the given <a href="#binary-name">name</a> that 2233 * has been defined by this class loader. 2234 * 2235 * @param name The <a href="#binary-name">package name</a> 2236 * 2237 * @return The {@code Package} of the given name that has been defined 2238 * by this class loader, or {@code null} if not found 2239 * 2240 * @throws NullPointerException 2241 * if {@code name} is {@code null}. 2242 * 2243 * @jvms 5.3 Creation and Loading 2244 * 2245 * @since 9 2246 * @spec JPMS 2247 */ 2248 public final Package getDefinedPackage(String name) { 2249 Objects.requireNonNull(name, "name cannot be null"); 2250 2251 NamedPackage p = packages.get(name); 2252 if (p == null) 2253 return null; 2254 2255 return definePackage(name, p.module()); 2256 } 2257 2258 /** 2259 * Returns all of the {@code Package}s that have been defined by 2260 * this class loader. The returned array has no duplicated {@code Package}s 2261 * of the same name. 2262 * 2263 * @apiNote This method returns an array rather than a {@code Set} or {@code Stream} 2264 * for consistency with the existing {@link #getPackages} method. 2265 * 2266 * @return The array of {@code Package} objects that have been defined by 2267 * this class loader; or an zero length array if no package has been 2268 * defined by this class loader. 2269 * 2270 * @jvms 5.3 Creation and Loading 2271 * 2272 * @since 9 2273 * @spec JPMS 2274 */ 2275 public final Package[] getDefinedPackages() { 2276 return packages().toArray(Package[]::new); 2277 } 2278 2279 /** 2280 * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors. 2281 * <p> 2282 * If this class loader defines a {@code Package} of the given name, 2283 * the {@code Package} is returned. Otherwise, the ancestors of 2284 * this class loader are searched recursively (parent by parent) 2285 * for a {@code Package} of the given name. 2286 * 2287 * @apiNote The {@link #getPlatformClassLoader() platform class loader} 2288 * may delegate to the application class loader but the application class 2289 * loader is not its ancestor. When invoked on the platform class loader, 2290 * this method will not find packages defined to the application 2291 * class loader. 2292 * 2293 * @param name 2294 * The <a href="#binary-name">package name</a> 2295 * 2296 * @return The {@code Package} of the given name that has been defined by 2297 * this class loader or its ancestors, or {@code null} if not found. 2298 * 2299 * @throws NullPointerException 2300 * if {@code name} is {@code null}. 2301 * 2302 * @deprecated 2303 * If multiple class loaders delegate to each other and define classes 2304 * with the same package name, and one such loader relies on the lookup 2305 * behavior of {@code getPackage} to return a {@code Package} from 2306 * a parent loader, then the properties exposed by the {@code Package} 2307 * may not be as expected in the rest of the program. 2308 * For example, the {@code Package} will only expose annotations from the 2309 * {@code package-info.class} file defined by the parent loader, even if 2310 * annotations exist in a {@code package-info.class} file defined by 2311 * a child loader. A more robust approach is to use the 2312 * {@link ClassLoader#getDefinedPackage} method which returns 2313 * a {@code Package} for the specified class loader. 2314 * 2315 * @see ClassLoader#getDefinedPackage(String) 2316 * 2317 * @since 1.2 2318 * @revised 9 2319 * @spec JPMS 2320 */ 2321 @Deprecated(since="9") 2322 protected Package getPackage(String name) { 2323 Package pkg = getDefinedPackage(name); 2324 if (pkg == null) { 2325 if (parent != null) { 2326 pkg = parent.getPackage(name); 2327 } else { 2328 pkg = BootLoader.getDefinedPackage(name); 2329 } 2330 } 2331 return pkg; 2332 } 2333 2334 /** 2335 * Returns all of the {@code Package}s that have been defined by 2336 * this class loader and its ancestors. The returned array may contain 2337 * more than one {@code Package} object of the same package name, each 2338 * defined by a different class loader in the class loader hierarchy. 2339 * 2340 * @apiNote The {@link #getPlatformClassLoader() platform class loader} 2341 * may delegate to the application class loader. In other words, 2342 * packages in modules defined to the application class loader may be 2343 * visible to the platform class loader. On the other hand, 2344 * the application class loader is not its ancestor and hence 2345 * when invoked on the platform class loader, this method will not 2346 * return any packages defined to the application class loader. 2347 * 2348 * @return The array of {@code Package} objects that have been defined by 2349 * this class loader and its ancestors 2350 * 2351 * @see ClassLoader#getDefinedPackages() 2352 * 2353 * @since 1.2 2354 * @revised 9 2355 * @spec JPMS 2356 */ 2357 protected Package[] getPackages() { 2358 Stream<Package> pkgs = packages(); 2359 ClassLoader ld = parent; 2360 while (ld != null) { 2361 pkgs = Stream.concat(ld.packages(), pkgs); 2362 ld = ld.parent; 2363 } 2364 return Stream.concat(BootLoader.packages(), pkgs) 2365 .toArray(Package[]::new); 2366 } 2367 2368 2369 2370 // package-private 2371 2372 /** 2373 * Returns a stream of Packages defined in this class loader 2374 */ 2375 Stream<Package> packages() { 2376 return packages.values().stream() 2377 .map(p -> definePackage(p.packageName(), p.module())); 2378 } 2379 2380 // -- Native library access -- 2381 2382 /** 2383 * Returns the absolute path name of a native library. The VM invokes this 2384 * method to locate the native libraries that belong to classes loaded with 2385 * this class loader. If this method returns {@code null}, the VM 2386 * searches the library along the path specified as the 2387 * "{@code java.library.path}" property. 2388 * 2389 * @param libname 2390 * The library name 2391 * 2392 * @return The absolute path of the native library 2393 * 2394 * @see System#loadLibrary(String) 2395 * @see System#mapLibraryName(String) 2396 * 2397 * @since 1.2 2398 */ 2399 protected String findLibrary(String libname) { 2400 return null; 2401 } 2402 2403 /** 2404 * The inner class NativeLibrary denotes a loaded native library instance. 2405 * Every classloader contains a vector of loaded native libraries in the 2406 * private field {@code nativeLibraries}. The native libraries loaded 2407 * into the system are entered into the {@code systemNativeLibraries} 2408 * vector. 2409 * 2410 * <p> Every native library requires a particular version of JNI. This is 2411 * denoted by the private {@code jniVersion} field. This field is set by 2412 * the VM when it loads the library, and used by the VM to pass the correct 2413 * version of JNI to the native methods. </p> 2414 * 2415 * @see ClassLoader 2416 * @since 1.2 2417 */ 2418 static class NativeLibrary { 2419 // the class from which the library is loaded, also indicates 2420 // the loader this native library belongs. 2421 final Class<?> fromClass; 2422 // the canonicalized name of the native library. 2423 // or static library name 2424 final String name; 2425 // Indicates if the native library is linked into the VM 2426 final boolean isBuiltin; 2427 2428 // opaque handle to native library, used in native code. 2429 long handle; 2430 // the version of JNI environment the native library requires. 2431 int jniVersion; 2432 2433 native boolean load0(String name, boolean isBuiltin); 2434 2435 native long findEntry(String name); 2436 2437 NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) { 2438 this.name = name; 2439 this.fromClass = fromClass; 2440 this.isBuiltin = isBuiltin; 2441 } 2442 2443 /* 2444 * Loads the native library and registers for cleanup when its 2445 * associated class loader is unloaded 2446 */ 2447 boolean load() { 2448 if (handle != 0) { 2449 throw new InternalError("Native library " + name + " has been loaded"); 2450 } 2451 2452 if (!load0(name, isBuiltin)) return false; 2453 2454 // register the class loader for cleanup when unloaded 2455 // builtin class loaders are never unloaded 2456 ClassLoader loader = fromClass.getClassLoader(); 2457 if (loader != null && 2458 loader != getBuiltinPlatformClassLoader() && 2459 loader != getBuiltinAppClassLoader()) { 2460 CleanerFactory.cleaner().register(loader, 2461 new Unloader(name, handle, isBuiltin)); 2462 } 2463 return true; 2464 } 2465 2466 static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) { 2467 ClassLoader loader = 2468 fromClass == null ? null : fromClass.getClassLoader(); 2469 2470 synchronized (loadedLibraryNames) { 2471 Map<String, NativeLibrary> libs = 2472 loader != null ? loader.nativeLibraries() : systemNativeLibraries(); 2473 if (libs.containsKey(name)) { 2474 return true; 2475 } 2476 2477 if (loadedLibraryNames.contains(name)) { 2478 throw new UnsatisfiedLinkError("Native Library " + name + 2479 " already loaded in another classloader"); 2480 } 2481 2482 /* 2483 * When a library is being loaded, JNI_OnLoad function can cause 2484 * another loadLibrary invocation that should succeed. 2485 * 2486 * We use a static stack to hold the list of libraries we are 2487 * loading because this can happen only when called by the 2488 * same thread because this block is synchronous. 2489 * 2490 * If there is a pending load operation for the library, we 2491 * immediately return success; otherwise, we raise 2492 * UnsatisfiedLinkError. 2493 */ 2494 for (NativeLibrary lib : nativeLibraryContext) { 2495 if (name.equals(lib.name)) { 2496 if (loader == lib.fromClass.getClassLoader()) { 2497 return true; 2498 } else { 2499 throw new UnsatisfiedLinkError("Native Library " + 2500 name + " is being loaded in another classloader"); 2501 } 2502 } 2503 } 2504 NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin); 2505 // load the native library 2506 nativeLibraryContext.push(lib); 2507 try { 2508 if (!lib.load()) return false; 2509 } finally { 2510 nativeLibraryContext.pop(); 2511 } 2512 // register the loaded native library 2513 loadedLibraryNames.add(name); 2514 libs.put(name, lib); 2515 } 2516 return true; 2517 } 2518 2519 // Invoked in the VM to determine the context class in JNI_OnLoad 2520 // and JNI_OnUnload 2521 static Class<?> getFromClass() { 2522 return nativeLibraryContext.peek().fromClass; 2523 } 2524 2525 // native libraries being loaded 2526 static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8); 2527 2528 /* 2529 * The run() method will be invoked when this class loader becomes 2530 * phantom reachable to unload the native library. 2531 */ 2532 static class Unloader implements Runnable { 2533 // This represents the context when a native library is unloaded 2534 // and getFromClass() will return null, 2535 static final NativeLibrary UNLOADER = 2536 new NativeLibrary(null, "dummy", false); 2537 final String name; 2538 final long handle; 2539 final boolean isBuiltin; 2540 2541 Unloader(String name, long handle, boolean isBuiltin) { 2542 if (handle == 0) { 2543 throw new IllegalArgumentException( 2544 "Invalid handle for native library " + name); 2545 } 2546 2547 this.name = name; 2548 this.handle = handle; 2549 this.isBuiltin = isBuiltin; 2550 } 2551 2552 @Override 2553 public void run() { 2554 synchronized (loadedLibraryNames) { 2555 /* remove the native library name */ 2556 loadedLibraryNames.remove(name); 2557 nativeLibraryContext.push(UNLOADER); 2558 try { 2559 unload(name, isBuiltin, handle); 2560 } finally { 2561 nativeLibraryContext.pop(); 2562 } 2563 2564 } 2565 } 2566 } 2567 2568 // JNI FindClass expects the caller class if invoked from JNI_OnLoad 2569 // and JNI_OnUnload is NativeLibrary class 2570 static native void unload(String name, boolean isBuiltin, long handle); 2571 } 2572 2573 // The paths searched for libraries 2574 private static String usr_paths[]; 2575 private static String sys_paths[]; 2576 2577 private static String[] initializePath(String propName) { 2578 String ldPath = System.getProperty(propName, ""); 2579 int ldLen = ldPath.length(); 2580 char ps = File.pathSeparatorChar; 2581 int psCount = 0; 2582 2583 if (ClassLoaderHelper.allowsQuotedPathElements && 2584 ldPath.indexOf('\"') >= 0) { 2585 // First, remove quotes put around quoted parts of paths. 2586 // Second, use a quotation mark as a new path separator. 2587 // This will preserve any quoted old path separators. 2588 char[] buf = new char[ldLen]; 2589 int bufLen = 0; 2590 for (int i = 0; i < ldLen; ++i) { 2591 char ch = ldPath.charAt(i); 2592 if (ch == '\"') { 2593 while (++i < ldLen && 2594 (ch = ldPath.charAt(i)) != '\"') { 2595 buf[bufLen++] = ch; 2596 } 2597 } else { 2598 if (ch == ps) { 2599 psCount++; 2600 ch = '\"'; 2601 } 2602 buf[bufLen++] = ch; 2603 } 2604 } 2605 ldPath = new String(buf, 0, bufLen); 2606 ldLen = bufLen; 2607 ps = '\"'; 2608 } else { 2609 for (int i = ldPath.indexOf(ps); i >= 0; 2610 i = ldPath.indexOf(ps, i + 1)) { 2611 psCount++; 2612 } 2613 } 2614 2615 String[] paths = new String[psCount + 1]; 2616 int pathStart = 0; 2617 for (int j = 0; j < psCount; ++j) { 2618 int pathEnd = ldPath.indexOf(ps, pathStart); 2619 paths[j] = (pathStart < pathEnd) ? 2620 ldPath.substring(pathStart, pathEnd) : "."; 2621 pathStart = pathEnd + 1; 2622 } 2623 paths[psCount] = (pathStart < ldLen) ? 2624 ldPath.substring(pathStart, ldLen) : "."; 2625 return paths; 2626 } 2627 2628 // Invoked in the java.lang.Runtime class to implement load and loadLibrary. 2629 static void loadLibrary(Class<?> fromClass, String name, 2630 boolean isAbsolute) { 2631 ClassLoader loader = 2632 (fromClass == null) ? null : fromClass.getClassLoader(); 2633 assert sys_paths != null : "should be initialized at this point"; 2634 assert usr_paths != null : "should be initialized at this point"; 2635 2636 if (isAbsolute) { 2637 if (loadLibrary0(fromClass, new File(name))) { 2638 return; 2639 } 2640 throw new UnsatisfiedLinkError("Can't load library: " + name); 2641 } 2642 if (loader != null) { 2643 String libfilename = loader.findLibrary(name); 2644 if (libfilename != null) { 2645 File libfile = new File(libfilename); 2646 if (!libfile.isAbsolute()) { 2647 throw new UnsatisfiedLinkError( 2648 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename); 2649 } 2650 if (loadLibrary0(fromClass, libfile)) { 2651 return; 2652 } 2653 throw new UnsatisfiedLinkError("Can't load " + libfilename); 2654 } 2655 } 2656 for (String sys_path : sys_paths) { 2657 File libfile = new File(sys_path, System.mapLibraryName(name)); 2658 if (loadLibrary0(fromClass, libfile)) { 2659 return; 2660 } 2661 libfile = ClassLoaderHelper.mapAlternativeName(libfile); 2662 if (libfile != null && loadLibrary0(fromClass, libfile)) { 2663 return; 2664 } 2665 } 2666 if (loader != null) { 2667 for (String usr_path : usr_paths) { 2668 File libfile = new File(usr_path, System.mapLibraryName(name)); 2669 if (loadLibrary0(fromClass, libfile)) { 2670 return; 2671 } 2672 libfile = ClassLoaderHelper.mapAlternativeName(libfile); 2673 if (libfile != null && loadLibrary0(fromClass, libfile)) { 2674 return; 2675 } 2676 } 2677 } 2678 // Oops, it failed 2679 throw new UnsatisfiedLinkError("no " + name + 2680 " in java.library.path: " + Arrays.toString(usr_paths)); 2681 } 2682 2683 private static native String findBuiltinLib(String name); 2684 2685 private static boolean loadLibrary0(Class<?> fromClass, final File file) { 2686 // Check to see if we're attempting to access a static library 2687 String name = findBuiltinLib(file.getName()); 2688 boolean isBuiltin = (name != null); 2689 if (!isBuiltin) { 2690 name = AccessController.doPrivileged( 2691 new PrivilegedAction<>() { 2692 public String run() { 2693 try { 2694 return file.exists() ? file.getCanonicalPath() : null; 2695 } catch (IOException e) { 2696 return null; 2697 } 2698 } 2699 }); 2700 if (name == null) { 2701 return false; 2702 } 2703 } 2704 return NativeLibrary.loadLibrary(fromClass, name, isBuiltin); 2705 } 2706 2707 /* 2708 * Invoked in the VM class linking code. 2709 */ 2710 private static long findNative(ClassLoader loader, String entryName) { 2711 Map<String, NativeLibrary> libs = 2712 loader != null ? loader.nativeLibraries() : systemNativeLibraries(); 2713 if (libs.isEmpty()) 2714 return 0; 2715 2716 // the native libraries map may be updated in another thread 2717 // when a native library is being loaded. No symbol will be 2718 // searched from it yet. 2719 for (NativeLibrary lib : libs.values()) { 2720 long entry = lib.findEntry(entryName); 2721 if (entry != 0) return entry; 2722 } 2723 return 0; 2724 } 2725 2726 // All native library names we've loaded. 2727 // This also serves as the lock to obtain nativeLibraries 2728 // and write to nativeLibraryContext. 2729 private static final Set<String> loadedLibraryNames = new HashSet<>(); 2730 2731 // Native libraries belonging to system classes. 2732 private static volatile Map<String, NativeLibrary> systemNativeLibraries; 2733 2734 // Native libraries associated with the class loader. 2735 private volatile Map<String, NativeLibrary> nativeLibraries; 2736 2737 /* 2738 * Returns the native libraries map associated with bootstrap class loader 2739 * This method will create the map at the first time when called. 2740 */ 2741 private static Map<String, NativeLibrary> systemNativeLibraries() { 2742 Map<String, NativeLibrary> libs = systemNativeLibraries; 2743 if (libs == null) { 2744 synchronized (loadedLibraryNames) { 2745 libs = systemNativeLibraries; 2746 if (libs == null) { 2747 libs = systemNativeLibraries = new ConcurrentHashMap<>(); 2748 } 2749 } 2750 } 2751 return libs; 2752 } 2753 2754 /* 2755 * Returns the native libraries map associated with this class loader 2756 * This method will create the map at the first time when called. 2757 */ 2758 private Map<String, NativeLibrary> nativeLibraries() { 2759 Map<String, NativeLibrary> libs = nativeLibraries; 2760 if (libs == null) { 2761 synchronized (loadedLibraryNames) { 2762 libs = nativeLibraries; 2763 if (libs == null) { 2764 libs = nativeLibraries = new ConcurrentHashMap<>(); 2765 } 2766 } 2767 } 2768 return libs; 2769 } 2770 2771 // -- Assertion management -- 2772 2773 final Object assertionLock; 2774 2775 // The default toggle for assertion checking. 2776 // @GuardedBy("assertionLock") 2777 private boolean defaultAssertionStatus = false; 2778 2779 // Maps String packageName to Boolean package default assertion status Note 2780 // that the default package is placed under a null map key. If this field 2781 // is null then we are delegating assertion status queries to the VM, i.e., 2782 // none of this ClassLoader's assertion status modification methods have 2783 // been invoked. 2784 // @GuardedBy("assertionLock") 2785 private Map<String, Boolean> packageAssertionStatus = null; 2786 2787 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this 2788 // field is null then we are delegating assertion status queries to the VM, 2789 // i.e., none of this ClassLoader's assertion status modification methods 2790 // have been invoked. 2791 // @GuardedBy("assertionLock") 2792 Map<String, Boolean> classAssertionStatus = null; 2793 2794 /** 2795 * Sets the default assertion status for this class loader. This setting 2796 * determines whether classes loaded by this class loader and initialized 2797 * in the future will have assertions enabled or disabled by default. 2798 * This setting may be overridden on a per-package or per-class basis by 2799 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link 2800 * #setClassAssertionStatus(String, boolean)}. 2801 * 2802 * @param enabled 2803 * {@code true} if classes loaded by this class loader will 2804 * henceforth have assertions enabled by default, {@code false} 2805 * if they will have assertions disabled by default. 2806 * 2807 * @since 1.4 2808 */ 2809 public void setDefaultAssertionStatus(boolean enabled) { 2810 synchronized (assertionLock) { 2811 if (classAssertionStatus == null) 2812 initializeJavaAssertionMaps(); 2813 2814 defaultAssertionStatus = enabled; 2815 } 2816 } 2817 2818 /** 2819 * Sets the package default assertion status for the named package. The 2820 * package default assertion status determines the assertion status for 2821 * classes initialized in the future that belong to the named package or 2822 * any of its "subpackages". 2823 * 2824 * <p> A subpackage of a package named p is any package whose name begins 2825 * with "{@code p.}". For example, {@code javax.swing.text} is a 2826 * subpackage of {@code javax.swing}, and both {@code java.util} and 2827 * {@code java.lang.reflect} are subpackages of {@code java}. 2828 * 2829 * <p> In the event that multiple package defaults apply to a given class, 2830 * the package default pertaining to the most specific package takes 2831 * precedence over the others. For example, if {@code javax.lang} and 2832 * {@code javax.lang.reflect} both have package defaults associated with 2833 * them, the latter package default applies to classes in 2834 * {@code javax.lang.reflect}. 2835 * 2836 * <p> Package defaults take precedence over the class loader's default 2837 * assertion status, and may be overridden on a per-class basis by invoking 2838 * {@link #setClassAssertionStatus(String, boolean)}. </p> 2839 * 2840 * @param packageName 2841 * The name of the package whose package default assertion status 2842 * is to be set. A {@code null} value indicates the unnamed 2843 * package that is "current" 2844 * (see section 7.4.2 of 2845 * <cite>The Java™ Language Specification</cite>.) 2846 * 2847 * @param enabled 2848 * {@code true} if classes loaded by this classloader and 2849 * belonging to the named package or any of its subpackages will 2850 * have assertions enabled by default, {@code false} if they will 2851 * have assertions disabled by default. 2852 * 2853 * @since 1.4 2854 */ 2855 public void setPackageAssertionStatus(String packageName, 2856 boolean enabled) { 2857 synchronized (assertionLock) { 2858 if (packageAssertionStatus == null) 2859 initializeJavaAssertionMaps(); 2860 2861 packageAssertionStatus.put(packageName, enabled); 2862 } 2863 } 2864 2865 /** 2866 * Sets the desired assertion status for the named top-level class in this 2867 * class loader and any nested classes contained therein. This setting 2868 * takes precedence over the class loader's default assertion status, and 2869 * over any applicable per-package default. This method has no effect if 2870 * the named class has already been initialized. (Once a class is 2871 * initialized, its assertion status cannot change.) 2872 * 2873 * <p> If the named class is not a top-level class, this invocation will 2874 * have no effect on the actual assertion status of any class. </p> 2875 * 2876 * @param className 2877 * The fully qualified class name of the top-level class whose 2878 * assertion status is to be set. 2879 * 2880 * @param enabled 2881 * {@code true} if the named class is to have assertions 2882 * enabled when (and if) it is initialized, {@code false} if the 2883 * class is to have assertions disabled. 2884 * 2885 * @since 1.4 2886 */ 2887 public void setClassAssertionStatus(String className, boolean enabled) { 2888 synchronized (assertionLock) { 2889 if (classAssertionStatus == null) 2890 initializeJavaAssertionMaps(); 2891 2892 classAssertionStatus.put(className, enabled); 2893 } 2894 } 2895 2896 /** 2897 * Sets the default assertion status for this class loader to 2898 * {@code false} and discards any package defaults or class assertion 2899 * status settings associated with the class loader. This method is 2900 * provided so that class loaders can be made to ignore any command line or 2901 * persistent assertion status settings and "start with a clean slate." 2902 * 2903 * @since 1.4 2904 */ 2905 public void clearAssertionStatus() { 2906 /* 2907 * Whether or not "Java assertion maps" are initialized, set 2908 * them to empty maps, effectively ignoring any present settings. 2909 */ 2910 synchronized (assertionLock) { 2911 classAssertionStatus = new HashMap<>(); 2912 packageAssertionStatus = new HashMap<>(); 2913 defaultAssertionStatus = false; 2914 } 2915 } 2916 2917 /** 2918 * Returns the assertion status that would be assigned to the specified 2919 * class if it were to be initialized at the time this method is invoked. 2920 * If the named class has had its assertion status set, the most recent 2921 * setting will be returned; otherwise, if any package default assertion 2922 * status pertains to this class, the most recent setting for the most 2923 * specific pertinent package default assertion status is returned; 2924 * otherwise, this class loader's default assertion status is returned. 2925 * </p> 2926 * 2927 * @param className 2928 * The fully qualified class name of the class whose desired 2929 * assertion status is being queried. 2930 * 2931 * @return The desired assertion status of the specified class. 2932 * 2933 * @see #setClassAssertionStatus(String, boolean) 2934 * @see #setPackageAssertionStatus(String, boolean) 2935 * @see #setDefaultAssertionStatus(boolean) 2936 * 2937 * @since 1.4 2938 */ 2939 boolean desiredAssertionStatus(String className) { 2940 synchronized (assertionLock) { 2941 // assert classAssertionStatus != null; 2942 // assert packageAssertionStatus != null; 2943 2944 // Check for a class entry 2945 Boolean result = classAssertionStatus.get(className); 2946 if (result != null) 2947 return result.booleanValue(); 2948 2949 // Check for most specific package entry 2950 int dotIndex = className.lastIndexOf('.'); 2951 if (dotIndex < 0) { // default package 2952 result = packageAssertionStatus.get(null); 2953 if (result != null) 2954 return result.booleanValue(); 2955 } 2956 while(dotIndex > 0) { 2957 className = className.substring(0, dotIndex); 2958 result = packageAssertionStatus.get(className); 2959 if (result != null) 2960 return result.booleanValue(); 2961 dotIndex = className.lastIndexOf('.', dotIndex-1); 2962 } 2963 2964 // Return the classloader default 2965 return defaultAssertionStatus; 2966 } 2967 } 2968 2969 // Set up the assertions with information provided by the VM. 2970 // Note: Should only be called inside a synchronized block 2971 private void initializeJavaAssertionMaps() { 2972 // assert Thread.holdsLock(assertionLock); 2973 2974 classAssertionStatus = new HashMap<>(); 2975 packageAssertionStatus = new HashMap<>(); 2976 AssertionStatusDirectives directives = retrieveDirectives(); 2977 2978 for(int i = 0; i < directives.classes.length; i++) 2979 classAssertionStatus.put(directives.classes[i], 2980 directives.classEnabled[i]); 2981 2982 for(int i = 0; i < directives.packages.length; i++) 2983 packageAssertionStatus.put(directives.packages[i], 2984 directives.packageEnabled[i]); 2985 2986 defaultAssertionStatus = directives.deflt; 2987 } 2988 2989 // Retrieves the assertion directives from the VM. 2990 private static native AssertionStatusDirectives retrieveDirectives(); 2991 2992 2993 // -- Misc -- 2994 2995 /** 2996 * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s) 2997 * associated with this ClassLoader, creating it if it doesn't already exist. 2998 */ 2999 ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() { 3000 ConcurrentHashMap<?, ?> map = classLoaderValueMap; 3001 if (map == null) { 3002 map = new ConcurrentHashMap<>(); 3003 boolean set = trySetObjectField("classLoaderValueMap", map); 3004 if (!set) { 3005 // beaten by someone else 3006 map = classLoaderValueMap; 3007 } 3008 } 3009 return map; 3010 } 3011 3012 // the storage for ClassLoaderValue(s) associated with this ClassLoader 3013 private volatile ConcurrentHashMap<?, ?> classLoaderValueMap; 3014 3015 /** 3016 * Attempts to atomically set a volatile field in this object. Returns 3017 * {@code true} if not beaten by another thread. Avoids the use of 3018 * AtomicReferenceFieldUpdater in this class. 3019 */ 3020 private boolean trySetObjectField(String name, Object obj) { 3021 Unsafe unsafe = Unsafe.getUnsafe(); 3022 Class<?> k = ClassLoader.class; 3023 long offset; 3024 offset = unsafe.objectFieldOffset(k, name); 3025 return unsafe.compareAndSetReference(this, offset, null, obj); 3026 } 3027 } 3028 3029 /* 3030 * A utility class that will enumerate over an array of enumerations. 3031 */ 3032 final class CompoundEnumeration<E> implements Enumeration<E> { 3033 private final Enumeration<E>[] enums; 3034 private int index; 3035 3036 public CompoundEnumeration(Enumeration<E>[] enums) { 3037 this.enums = enums; 3038 } 3039 3040 private boolean next() { 3041 while (index < enums.length) { 3042 if (enums[index] != null && enums[index].hasMoreElements()) { 3043 return true; 3044 } 3045 index++; 3046 } 3047 return false; 3048 } 3049 3050 public boolean hasMoreElements() { 3051 return next(); 3052 } 3053 3054 public E nextElement() { 3055 if (!next()) { 3056 throw new NoSuchElementException(); 3057 } 3058 return enums[index].nextElement(); 3059 } 3060 }