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