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