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