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