1 /*
2 * Copyright (c) 2012, 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 package java.lang;
26
27 import java.io.InputStream;
28 import java.io.IOException;
29 import java.io.File;
30 import java.lang.reflect.Constructor;
31 import java.lang.reflect.InvocationTargetException;
32 import java.net.MalformedURLException;
33 import java.net.URL;
34 import java.security.AccessController;
35 import java.security.AccessControlContext;
36 import java.security.CodeSource;
37 import java.security.Policy;
38 import java.security.PrivilegedAction;
39 import java.security.PrivilegedActionException;
40 import java.security.PrivilegedExceptionAction;
41 import java.security.ProtectionDomain;
42 import java.security.cert.Certificate;
43 import java.util.Collections;
44 import java.util.Enumeration;
45 import java.util.HashMap;
46 import java.util.HashSet;
47 import java.util.Set;
48 import java.util.Stack;
49 import java.util.Map;
50 import java.util.Vector;
51 import java.util.Hashtable;
52 import java.util.WeakHashMap;
53 import java.util.concurrent.ConcurrentHashMap;
54 import sun.misc.ClassFileTransformer;
55 import sun.misc.CompoundEnumeration;
56 import sun.misc.Resource;
57 import sun.misc.URLClassPath;
58 import sun.misc.VM;
59 import sun.reflect.Reflection;
60 import sun.security.util.SecurityConstants;
61
62 /**
63 * A class loader is an object that is responsible for loading classes. The
64 * class <tt>ClassLoader</tt> is an abstract class. Given the <a
65 * href="#name">binary name</a> of a class, a class loader should attempt to
66 * locate or generate data that constitutes a definition for the class. A
67 * typical strategy is to transform the name into a file name and then read a
68 * "class file" of that name from a file system.
69 *
70 * <p> Every {@link Class <tt>Class</tt>} object contains a {@link
71 * Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
72 * it.
73 *
74 * <p> <tt>Class</tt> objects for array classes are not created by class
75 * loaders, but are created automatically as required by the Java runtime.
76 * The class loader for an array class, as returned by {@link
77 * Class#getClassLoader()} is the same as the class loader for its element
78 * type; if the element type is a primitive type, then the array class has no
79 * class loader.
80 *
81 * <p> Applications implement subclasses of <tt>ClassLoader</tt> in order to
82 * extend the manner in which the Java virtual machine dynamically loads
83 * classes.
84 *
85 * <p> Class loaders may typically be used by security managers to indicate
86 * security domains.
87 *
88 * <p> The <tt>ClassLoader</tt> class uses a delegation model to search for
89 * classes and resources. Each instance of <tt>ClassLoader</tt> has an
90 * associated parent class loader. When requested to find a class or
91 * resource, a <tt>ClassLoader</tt> instance will delegate the search for the
92 * class or resource to its parent class loader before attempting to find the
93 * class or resource itself. The virtual machine's built-in class loader,
94 * called the "bootstrap class loader", does not itself have a parent but may
95 * serve as the parent of a <tt>ClassLoader</tt> instance.
96 *
97 * <p> Class loaders that support concurrent loading of classes are known as
98 * <em>parallel capable</em> class loaders and are required to register
99 * themselves at their class initialization time by invoking the
100 * {@link
101 * #registerAsParallelCapable <tt>ClassLoader.registerAsParallelCapable</tt>}
102 * method. Note that the <tt>ClassLoader</tt> class is registered as parallel
103 * capable by default. However, its subclasses still need to register themselves
104 * if they are parallel capable. <br>
105 * In environments in which the delegation model is not strictly
106 * hierarchical, class loaders need to be parallel capable, otherwise class
107 * loading can lead to deadlocks because the loader lock is held for the
108 * duration of the class loading process (see {@link #loadClass
109 * <tt>loadClass</tt>} methods).
110 *
111 * <p>Regular parallel capable class loaders may still need to use some form
112 * of synchronization to control concurrent load attempts of a given class.
113 * The {@link #getClassLoadingLock getClassLoadingLock} method is used to
114 * provide that object for use by {@link #loadClass loadClass}. A class loader
115 * can support fully concurrent loading of any class, in which case no
116 * synchronization need be used. Such parallel capable class loaders are
117 * required to register themselves at their class initialization time by
118 * invoking the
119 * {@link #registerAsFullyConcurrent registerAsFullyConcurrent} method.
120 * Note that the <tt>ClassLoader</tt> class is registered as fully
121 * concurrent by default. However, its subclasses still need to register
122 * themselves if they capable of fully concurrent class loading.
123 *
124 * <p> Normally, the Java virtual machine loads classes from the local file
125 * system in a platform-dependent manner. For example, on UNIX systems, the
126 * virtual machine loads classes from the directory defined by the
127 * <tt>CLASSPATH</tt> environment variable.
128 *
129 * <p> However, some classes may not originate from a file; they may originate
130 * from other sources, such as the network, or they could be constructed by an
131 * application. The method {@link #defineClass(String, byte[], int, int)
132 * <tt>defineClass</tt>} converts an array of bytes into an instance of class
133 * <tt>Class</tt>. Instances of this newly defined class can be created using
134 * {@link Class#newInstance <tt>Class.newInstance</tt>}.
135 *
136 * <p> The methods and constructors of objects created by a class loader may
137 * reference other classes. To determine the class(es) referred to, the Java
138 * virtual machine invokes the {@link #loadClass <tt>loadClass</tt>} method of
139 * the class loader that originally created the class.
140 *
141 * <p> For example, an application could create a network class loader to
142 * download class files from a server. Sample code might look like:
143 *
144 * <blockquote><pre>
145 * ClassLoader loader = new NetworkClassLoader(host, port);
146 * Object main = loader.loadClass("Main", true).newInstance();
147 * . . .
148 * </pre></blockquote>
149 *
150 * <p> The network class loader subclass must define the methods {@link
151 * #findClass <tt>findClass</tt>} and <tt>loadClassData</tt> to load a class
152 * from the network. Once it has downloaded the bytes that make up the class,
153 * it should use the method {@link #defineClass <tt>defineClass</tt>} to
154 * create a class instance. A sample implementation is:
155 *
156 * <blockquote><pre>
157 * class NetworkClassLoader extends ClassLoader {
158 * String host;
159 * int port;
160 *
161 * public Class findClass(String name) {
162 * byte[] b = loadClassData(name);
163 * return defineClass(name, b, 0, b.length);
164 * }
165 *
166 * private byte[] loadClassData(String name) {
167 * // load the class data from the connection
168 * . . .
169 * }
170 * }
171 * </pre></blockquote>
172 *
173 * <h4> <a name="name">Binary names</a> </h4>
174 *
175 * <p> Any class name provided as a {@link String} parameter to methods in
176 * <tt>ClassLoader</tt> must be a binary name as defined by
177 * <cite>The Java™ Language Specification</cite>.
178 *
179 * <p> Examples of valid class names include:
180 * <blockquote><pre>
181 * "java.lang.String"
182 * "javax.swing.JSpinner$DefaultEditor"
183 * "java.security.KeyStore$Builder$FileBuilder$1"
184 * "java.net.URLClassLoader$3$1"
185 * </pre></blockquote>
186 *
187 * @see #resolveClass(Class)
188 * @since 1.0
189 */
190 public abstract class ClassLoader {
191
192 private static native void registerNatives();
193 static {
194 registerNatives();
195 }
196
197 // The parent class loader for delegation
198 // Note: VM hardcoded the offset of this field, thus all new fields
199 // must be added *after* it.
200 private final ClassLoader parent;
201
202 /**
203 * Encapsulates the set of parallel capable loader types.
204 */
205 private static class ParallelLoaders {
206 private ParallelLoaders() {}
207
208 // the set of parallel capable loader types
209 // - loader in the map -> parallel capable
210 // - loader maps to TRUE -> fully concurrent
211 private static final WeakHashMap<Class<? extends ClassLoader>,
212 Boolean> loaderTypes =
213 new WeakHashMap<>();
214
215 static {
216 synchronized (loaderTypes) { loaderTypes.put(ClassLoader.class, Boolean.TRUE); }
217 }
218
219 /**
220 * Registers the given class loader type as parallel capable.
221 * Returns {@code true} is successfully registered; {@code false} if
222 * loader's super class is not registered.
223 */
224 static boolean register(Class<? extends ClassLoader> c,
225 boolean fullyConcurrent) {
226 synchronized (loaderTypes) {
227 if (loaderTypes.containsKey(c.getSuperclass())) {
228 // register the class loader as parallel capable
229 // if and only if all of its super classes are.
230 // Note: given current classloading sequence, if
231 // the immediate super class is parallel capable,
232 // all the super classes higher up must be too.
233 loaderTypes.put(c, fullyConcurrent);
234 System.out.println("Registered: " + c.getName() + " as " +
235 (fullyConcurrent ? "fully concurrent " : " parallel capable") + " classloader");
236 return true;
237 } else {
238 return false;
239 }
240 }
241 }
242
243 /**
244 * Returns the value of the given loader in the parallel
245 * loader map, else null.
246 */
247 static Boolean getRegistration(Class<? extends ClassLoader> c) {
248 synchronized(loaderTypes) {
249 return loaderTypes.get(c);
250 }
251 }
252 }
253
254 // Maps class name to the corresponding lock object when the current
255 // class loader is parallel capable.
256 // Note: VM also uses this field to decide if the current class loader
257 // is parallel capable and the appropriate lock object for class loading.
258 private final ConcurrentHashMap<String, Object> parallelLockMap;
259
260 // Indicates this parallel capable loader supports fully concurrent loading
261 // Note: the VM uses this field to decide if the current class loader
262 // allows parallel class definition
263 private final boolean isFullyConcurrent;
264
265 // Indicate if this loader is parallel capable
266 private boolean isParallelCapable() {
267 return parallelLockMap != null || isFullyConcurrent;
268 }
269
270 // Hashtable that maps packages to certs
271 private final Map <String, Certificate[]> package2certs;
272
273 // Shared among all packages with unsigned classes
274 private static final Certificate[] nocerts = new Certificate[0];
275
276 // The classes loaded by this class loader. The only purpose of this table
277 // is to keep the classes from being GC'ed until the loader is GC'ed.
278 private final Vector<Class<?>> classes = new Vector<>();
279
280 // The "default" domain. Set as the default ProtectionDomain on newly
281 // created classes.
282 private final ProtectionDomain defaultDomain =
283 new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
284 null, this, null);
285
286 // The initiating protection domains for all classes loaded by this loader
287 private final Set<ProtectionDomain> domains;
288
289 // Invoked by the VM to record every loaded class with this loader.
290 void addClass(Class<?> c) {
291 classes.addElement(c);
292 }
293
294 // The packages defined in this class loader. Each package name is mapped
295 // to its corresponding Package object.
296 // @GuardedBy("itself")
297 private final HashMap<String, Package> packages = new HashMap<>();
298
299 private static Void checkCreateClassLoader() {
300 SecurityManager security = System.getSecurityManager();
301 if (security != null) {
302 security.checkCreateClassLoader();
303 }
304 return null;
305 }
306
307 private ClassLoader(Void unused, ClassLoader parent) {
308 this.parent = parent;
309 Boolean reg = ParallelLoaders.getRegistration(this.getClass());
310 if (reg != null) {
311 isFullyConcurrent = reg;
312 if (isFullyConcurrent)
313 parallelLockMap = null;
314 else
315 parallelLockMap = new ConcurrentHashMap<>();
316 package2certs = new ConcurrentHashMap<>();
317 domains =
318 Collections.synchronizedSet(new HashSet<ProtectionDomain>());
319 assertionLock = new Object();
320 } else {
321 // no finer-grained lock; lock on the classloader instance
322 isFullyConcurrent = false;
323 parallelLockMap = null;
324 package2certs = new Hashtable<>();
325 domains = new HashSet<>();
326 assertionLock = this;
327 }
328 }
329
330 /**
331 * Creates a new class loader using the specified parent class loader for
332 * delegation.
333 *
334 * <p> If there is a security manager, its {@link
335 * SecurityManager#checkCreateClassLoader()
336 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
337 * a security exception. </p>
338 *
339 * @param parent
340 * The parent class loader
341 *
342 * @throws SecurityException
343 * If a security manager exists and its
344 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
345 * of a new class loader.
346 *
347 * @since 1.2
348 */
349 protected ClassLoader(ClassLoader parent) {
350 this(checkCreateClassLoader(), parent);
351 }
352
353 /**
354 * Creates a new class loader using the <tt>ClassLoader</tt> returned by
355 * the method {@link #getSystemClassLoader()
356 * <tt>getSystemClassLoader()</tt>} as the parent class loader.
357 *
358 * <p> If there is a security manager, its {@link
359 * SecurityManager#checkCreateClassLoader()
360 * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
361 * a security exception. </p>
362 *
363 * @throws SecurityException
364 * If a security manager exists and its
365 * <tt>checkCreateClassLoader</tt> method doesn't allow creation
366 * of a new class loader.
367 */
368 protected ClassLoader() {
369 this(checkCreateClassLoader(), getSystemClassLoader());
370 }
371
372 // -- Class --
373
374 /**
375 * Loads the class with the specified <a href="#name">binary name</a>.
376 * This method searches for classes in the same manner as the {@link
377 * #loadClass(String, boolean)} method. It is invoked by the Java virtual
378 * machine to resolve class references. Invoking this method is equivalent
379 * to invoking {@link #loadClass(String, boolean) <tt>loadClass(name,
380 * false)</tt>}. </p>
381 *
382 * @param name
383 * The <a href="#name">binary name</a> of the class
384 *
385 * @return The resulting <tt>Class</tt> object
386 *
387 * @throws ClassNotFoundException
388 * If the class was not found
389 */
390 public Class<?> loadClass(String name) throws ClassNotFoundException {
391 return loadClass(name, false);
392 }
393
394 /**
395 * Loads the class with the specified <a href="#name">binary name</a>. The
396 * default implementation of this method searches for classes in the
397 * following order:
398 *
399 * <p><ol>
400 *
401 * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
402 * has already been loaded. </p></li>
403 *
404 * <li><p> Invoke the {@link #loadClass(String) <tt>loadClass</tt>} method
405 * on the parent class loader. If the parent is <tt>null</tt> the class
406 * loader built-in to the virtual machine is used, instead. </p></li>
407 *
408 * <li><p> Invoke the {@link #findClass(String)} method to find the
409 * class. </p></li>
410 *
411 * </ol>
412 *
413 * <p> If the class was found using the above steps, and the
414 * <tt>resolve</tt> flag is true, this method will then invoke the {@link
415 * #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
416 *
417 * <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
418 * #findClass(String)}, rather than this method. </p>
419 *
420 * <p> Unless overridden, if this loader is not fully concurrent then
421 * this method synchronizes on the result
422 * of the {@link #getClassLoadingLock <tt>getClassLoadingLock</tt>} method
423 * during the entire class loading process. For a fully concurrent loader
424 * no synchronization occurs.
425 *
426 * @param name
427 * The <a href="#name">binary name</a> of the class
428 *
429 * @param resolve
430 * If <tt>true</tt> then resolve the class
431 *
432 * @return The resulting <tt>Class</tt> object
433 *
434 * @throws ClassNotFoundException
435 * If the class could not be found
436 */
437 protected Class<?> loadClass(String name, boolean resolve)
438 throws ClassNotFoundException
439 {
440 Class<?> c = null;
441 if (!isFullyConcurrent) {
442 synchronized (getClassLoadingLock(name)) {
443 c = do_loadClass(name);
444 if (resolve) {
445 resolveClass(c);
446 }
447 }
448 }
449 else {
450 c = do_loadClass(name);
451 if (resolve) {
452 resolveClass(c);
453 }
454 }
455 return c;
456 }
457
458
459 private Class<?> do_loadClass(String name)
460 throws ClassNotFoundException
461 {
462 // First, check if the class has already been loaded
463 Class<?> c = findLoadedClass(name);
464 if (c == null) {
465 long t0 = System.nanoTime();
466 try {
467 if (parent != null) {
468 c = parent.loadClass(name, false);
469 } else {
470 c = findBootstrapClassOrNull(name);
471 }
472 } catch (ClassNotFoundException e) {
473 // ClassNotFoundException thrown if class not found
474 // from the non-null parent class loader
475 }
476
477 if (c == null) {
478 // If still not found, then invoke findClass in order
479 // to find the class.
480 long t1 = System.nanoTime();
481 c = findClass(name);
482
483 // this is the defining class loader; record the stats
484 sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
485 sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
486 sun.misc.PerfCounter.getFindClasses().increment();
487 }
488 }
489 return c;
490 }
491
492 /**
493 * Returns the lock object for class loading operations.
494 * For backward compatibility, the default implementation of this method
495 * behaves as follows. If this ClassLoader object is registered as
496 * parallel capable, the method returns a dedicated object associated
497 * with the specified class name. Otherwise, the method returns this
498 * ClassLoader object. </p>
499 *
500 * @param className
501 * The name of the to-be-loaded class
502 *
503 * @return the lock for class loading operations
504 *
505 * @throws NullPointerException
506 * If registered as parallel capable and <tt>className</tt> is null
507 *
508 * @see #loadClass(String, boolean)
509 *
510 * @since 1.7
511 */
512 protected Object getClassLoadingLock(String className) {
513 Object lock = this;
514 if (parallelLockMap != null) {
515 Object newLock = new Object();
516 lock = parallelLockMap.putIfAbsent(className, newLock);
517 if (lock == null) {
518 lock = newLock;
519 }
520 }
521 else if (isFullyConcurrent) {
522 lock = null; // TBD: is this the best thing to return?
523 }
524 return lock;
525 }
526
527 // This method is invoked by the virtual machine to load a class.
528 private Class<?> loadClassInternal(String name)
529 throws ClassNotFoundException
530 {
531 // For backward compatibility, explicitly lock on 'this' when
532 // the current class loader is not parallel capable.
533 if (!isParallelCapable()) {
534 synchronized (this) {
535 return loadClass(name);
536 }
537 } else {
538 return loadClass(name);
539 }
540 }
541
542 // Invoked by the VM after loading class with this loader.
543 private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
544 final SecurityManager sm = System.getSecurityManager();
545 if (sm != null) {
546 final String name = cls.getName();
547 final int i = name.lastIndexOf('.');
548 if (i != -1) {
549 AccessController.doPrivileged(new PrivilegedAction<Void>() {
550 public Void run() {
551 sm.checkPackageAccess(name.substring(0, i));
552 return null;
553 }
554 }, new AccessControlContext(new ProtectionDomain[] {pd}));
555 }
556 }
557 domains.add(pd);
558 }
559
560 /**
561 * Finds the class with the specified <a href="#name">binary name</a>.
562 * This method should be overridden by class loader implementations that
563 * follow the delegation model for loading classes, and will be invoked by
564 * the {@link #loadClass <tt>loadClass</tt>} method after checking the
565 * parent class loader for the requested class. The default implementation
566 * throws a <tt>ClassNotFoundException</tt>. </p>
567 *
568 * @param name
569 * The <a href="#name">binary name</a> of the class
570 *
571 * @return The resulting <tt>Class</tt> object
572 *
573 * @throws ClassNotFoundException
574 * If the class could not be found
575 *
576 * @since 1.2
577 */
578 protected Class<?> findClass(String name) throws ClassNotFoundException {
579 throw new ClassNotFoundException(name);
580 }
581
582 /**
583 * Converts an array of bytes into an instance of class <tt>Class</tt>.
584 * Before the <tt>Class</tt> can be used it must be resolved. This method
585 * is deprecated in favor of the version that takes a <a
586 * href="#name">binary name</a> as its first argument, and is more secure.
587 *
588 * @param b
589 * The bytes that make up the class data. The bytes in positions
590 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
591 * of a valid class file as defined by
592 * <cite>The Java™ Virtual Machine Specification</cite>.
593 *
594 * @param off
595 * The start offset in <tt>b</tt> of the class data
596 *
597 * @param len
598 * The length of the class data
599 *
600 * @return The <tt>Class</tt> object that was created from the specified
601 * class data
602 *
603 * @throws ClassFormatError
604 * If the data did not contain a valid class
605 *
606 * @throws IndexOutOfBoundsException
607 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
608 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
609 *
610 * @throws SecurityException
611 * If an attempt is made to add this class to a package that
612 * contains classes that were signed by a different set of
613 * certificates than this class, or if an attempt is made
614 * to define a class in a package with a fully-qualified name
615 * that starts with "{@code java.}".
616 *
617 * @see #loadClass(String, boolean)
618 * @see #resolveClass(Class)
619 *
620 * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
621 * defineClass(String, byte[], int, int)}
622 */
623 @Deprecated
624 protected final Class<?> defineClass(byte[] b, int off, int len)
625 throws ClassFormatError
626 {
627 return defineClass(null, b, off, len, null);
628 }
629
630 /**
631 * Converts an array of bytes into an instance of class <tt>Class</tt>.
632 * Before the <tt>Class</tt> can be used it must be resolved.
633 *
634 * <p> This method assigns a default {@link java.security.ProtectionDomain
635 * <tt>ProtectionDomain</tt>} to the newly defined class. The
636 * <tt>ProtectionDomain</tt> is effectively granted the same set of
637 * permissions returned when {@link
638 * java.security.Policy#getPermissions(java.security.CodeSource)
639 * <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
640 * is invoked. The default domain is created on the first invocation of
641 * {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
642 * and re-used on subsequent invocations.
643 *
644 * <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
645 * the {@link #defineClass(String, byte[], int, int,
646 * java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
647 * <tt>ProtectionDomain</tt> as one of its arguments. </p>
648 *
649 * @param name
650 * The expected <a href="#name">binary name</a> of the class, or
651 * <tt>null</tt> if not known
652 *
653 * @param b
654 * The bytes that make up the class data. The bytes in positions
655 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
656 * of a valid class file as defined by
657 * <cite>The Java™ Virtual Machine Specification</cite>.
658 *
659 * @param off
660 * The start offset in <tt>b</tt> of the class data
661 *
662 * @param len
663 * The length of the class data
664 *
665 * @return The <tt>Class</tt> object that was created from the specified
666 * class data.
667 *
668 * @throws ClassFormatError
669 * If the data did not contain a valid class
670 *
671 * @throws IndexOutOfBoundsException
672 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
673 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
674 *
675 * @throws SecurityException
676 * If an attempt is made to add this class to a package that
677 * contains classes that were signed by a different set of
678 * certificates than this class (which is unsigned), or if
679 * <tt>name</tt> begins with "<tt>java.</tt>".
680 *
681 * @see #loadClass(String, boolean)
682 * @see #resolveClass(Class)
683 * @see java.security.CodeSource
684 * @see java.security.SecureClassLoader
685 *
686 * @since 1.1
687 */
688 protected final Class<?> defineClass(String name, byte[] b, int off, int len)
689 throws ClassFormatError
690 {
691 return defineClass(name, b, off, len, null);
692 }
693
694 /* Determine protection domain, and check that:
695 - not define java.* class,
696 - signer of this class matches signers for the rest of the classes in
697 package.
698 */
699 private ProtectionDomain preDefineClass(String name,
700 ProtectionDomain pd)
701 {
702 if (!checkName(name))
703 throw new NoClassDefFoundError("IllegalName: " + name);
704
705 if ((name != null) && name.startsWith("java.")) {
706 throw new SecurityException
707 ("Prohibited package name: " +
708 name.substring(0, name.lastIndexOf('.')));
709 }
710 if (pd == null) {
711 pd = defaultDomain;
712 }
713
714 if (name != null) checkCerts(name, pd.getCodeSource());
715
716 return pd;
717 }
718
719 private String defineClassSourceLocation(ProtectionDomain pd)
720 {
721 CodeSource cs = pd.getCodeSource();
722 String source = null;
723 if (cs != null && cs.getLocation() != null) {
724 source = cs.getLocation().toString();
725 }
726 return source;
727 }
728
729 private Class<?> defineTransformedClass(String name, byte[] b, int off, int len,
730 ProtectionDomain pd,
731 ClassFormatError cfe, String source)
732 throws ClassFormatError
733 {
734 // Class format error - try to transform the bytecode and
735 // define the class again
736 //
737 ClassFileTransformer[] transformers =
738 ClassFileTransformer.getTransformers();
739 Class<?> c = null;
740
741 if (transformers != null) {
742 for (ClassFileTransformer transformer : transformers) {
743 try {
744 // Transform byte code using transformer
745 byte[] tb = transformer.transform(b, off, len);
746 c = defineClass1(name, tb, 0, tb.length,
747 pd, source);
748 break;
749 } catch (ClassFormatError cfe2) {
750 // If ClassFormatError occurs, try next transformer
751 }
752 }
753 }
754
755 // Rethrow original ClassFormatError if unable to transform
756 // bytecode to well-formed
757 //
758 if (c == null)
759 throw cfe;
760
761 return c;
762 }
763
764 private void postDefineClass(Class<?> c, ProtectionDomain pd)
765 {
766 if (pd.getCodeSource() != null) {
767 Certificate certs[] = pd.getCodeSource().getCertificates();
768 if (certs != null)
769 setSigners(c, certs);
770 }
771 }
772
773 /**
774 * Converts an array of bytes into an instance of class <tt>Class</tt>,
775 * with an optional <tt>ProtectionDomain</tt>. If the domain is
776 * <tt>null</tt>, then a default domain will be assigned to the class as
777 * specified in the documentation for {@link #defineClass(String, byte[],
778 * int, int)}. Before the class can be used it must be resolved.
779 *
780 * <p> The first class defined in a package determines the exact set of
781 * certificates that all subsequent classes defined in that package must
782 * contain. The set of certificates for a class is obtained from the
783 * {@link java.security.CodeSource <tt>CodeSource</tt>} within the
784 * <tt>ProtectionDomain</tt> of the class. Any classes added to that
785 * package must contain the same set of certificates or a
786 * <tt>SecurityException</tt> will be thrown. Note that if
787 * <tt>name</tt> is <tt>null</tt>, this check is not performed.
788 * You should always pass in the <a href="#name">binary name</a> of the
789 * class you are defining as well as the bytes. This ensures that the
790 * class you are defining is indeed the class you think it is.
791 *
792 * <p> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
793 * all classes in the "<tt>java.*</tt> packages can only be defined by the
794 * bootstrap class loader. If <tt>name</tt> is not <tt>null</tt>, it
795 * must be equal to the <a href="#name">binary name</a> of the class
796 * specified by the byte array "<tt>b</tt>", otherwise a {@link
797 * <tt>NoClassDefFoundError</tt>} will be thrown. </p>
798 *
799 * @param name
800 * The expected <a href="#name">binary name</a> of the class, or
801 * <tt>null</tt> if not known
802 *
803 * @param b
804 * The bytes that make up the class data. The bytes in positions
805 * <tt>off</tt> through <tt>off+len-1</tt> should have the format
806 * of a valid class file as defined by
807 * <cite>The Java™ Virtual Machine Specification</cite>.
808 *
809 * @param off
810 * The start offset in <tt>b</tt> of the class data
811 *
812 * @param len
813 * The length of the class data
814 *
815 * @param protectionDomain
816 * The ProtectionDomain of the class
817 *
818 * @return The <tt>Class</tt> object created from the data,
819 * and optional <tt>ProtectionDomain</tt>.
820 *
821 * @throws ClassFormatError
822 * If the data did not contain a valid class
823 *
824 * @throws NoClassDefFoundError
825 * If <tt>name</tt> is not equal to the <a href="#name">binary
826 * name</a> of the class specified by <tt>b</tt>
827 *
828 * @throws IndexOutOfBoundsException
829 * If either <tt>off</tt> or <tt>len</tt> is negative, or if
830 * <tt>off+len</tt> is greater than <tt>b.length</tt>.
831 *
832 * @throws SecurityException
833 * If an attempt is made to add this class to a package that
834 * contains classes that were signed by a different set of
835 * certificates than this class, or if <tt>name</tt> begins with
836 * "<tt>java.</tt>".
837 */
838 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
839 ProtectionDomain protectionDomain)
840 throws ClassFormatError
841 {
842 protectionDomain = preDefineClass(name, protectionDomain);
843
844 Class<?> c = null;
845 String source = defineClassSourceLocation(protectionDomain);
846
847 try {
848 c = defineClass1(name, b, off, len, protectionDomain, source);
849 } catch (ClassFormatError cfe) {
850 c = defineTransformedClass(name, b, off, len, protectionDomain, cfe,
851 source);
852 }
853
854 postDefineClass(c, protectionDomain);
855 return c;
856 }
857
858 /**
859 * Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
860 * into an instance of class <tt>Class</tt>,
861 * with an optional <tt>ProtectionDomain</tt>. If the domain is
862 * <tt>null</tt>, then a default domain will be assigned to the class as
863 * specified in the documentation for {@link #defineClass(String, byte[],
864 * int, int)}. Before the class can be used it must be resolved.
865 *
866 * <p>The rules about the first class defined in a package determining the
867 * set of certificates for the package, and the restrictions on class names
868 * are identical to those specified in the documentation for {@link
869 * #defineClass(String, byte[], int, int, ProtectionDomain)}.
870 *
871 * <p> An invocation of this method of the form
872 * <i>cl</i><tt>.defineClass(</tt><i>name</i><tt>,</tt>
873 * <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
874 * result as the statements
875 *
876 * <blockquote><tt>
877 * ...<br>
878 * byte[] temp = new byte[</tt><i>bBuffer</i><tt>.{@link
879 * java.nio.ByteBuffer#remaining remaining}()];<br>
880 * </tt><i>bBuffer</i><tt>.{@link java.nio.ByteBuffer#get(byte[])
881 * get}(temp);<br>
882 * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
883 * </tt><i>cl</i><tt>.defineClass}(</tt><i>name</i><tt>, temp, 0,
884 * temp.length, </tt><i>pd</i><tt>);<br>
885 * </tt></blockquote>
886 *
887 * @param name
888 * The expected <a href="#name">binary name</a>. of the class, or
889 * <tt>null</tt> if not known
890 *
891 * @param b
892 * The bytes that make up the class data. The bytes from positions
893 * <tt>b.position()</tt> through <tt>b.position() + b.limit() -1
894 * </tt> should have the format of a valid class file as defined by
895 * <cite>The Java™ Virtual Machine Specification</cite>.
896 *
897 * @param protectionDomain
898 * The ProtectionDomain of the class, or <tt>null</tt>.
899 *
900 * @return The <tt>Class</tt> object created from the data,
901 * and optional <tt>ProtectionDomain</tt>.
902 *
903 * @throws ClassFormatError
904 * If the data did not contain a valid class.
905 *
906 * @throws NoClassDefFoundError
907 * If <tt>name</tt> is not equal to the <a href="#name">binary
908 * name</a> of the class specified by <tt>b</tt>
909 *
910 * @throws SecurityException
911 * If an attempt is made to add this class to a package that
912 * contains classes that were signed by a different set of
913 * certificates than this class, or if <tt>name</tt> begins with
914 * "<tt>java.</tt>".
915 *
916 * @see #defineClass(String, byte[], int, int, ProtectionDomain)
917 *
918 * @since 1.5
919 */
920 protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
921 ProtectionDomain protectionDomain)
922 throws ClassFormatError
923 {
924 int len = b.remaining();
925
926 // Use byte[] if not a direct ByteBufer:
927 if (!b.isDirect()) {
928 if (b.hasArray()) {
929 return defineClass(name, b.array(),
930 b.position() + b.arrayOffset(), len,
931 protectionDomain);
932 } else {
933 // no array, or read-only array
934 byte[] tb = new byte[len];
935 b.get(tb); // get bytes out of byte buffer.
936 return defineClass(name, tb, 0, len, protectionDomain);
937 }
938 }
939
940 protectionDomain = preDefineClass(name, protectionDomain);
941
942 Class<?> c = null;
943 String source = defineClassSourceLocation(protectionDomain);
944
945 try {
946 c = defineClass2(name, b, b.position(), len, protectionDomain,
947 source);
948 } catch (ClassFormatError cfe) {
949 byte[] tb = new byte[len];
950 b.get(tb); // get bytes out of byte buffer.
951 c = defineTransformedClass(name, tb, 0, len, protectionDomain, cfe,
952 source);
953 }
954
955 postDefineClass(c, protectionDomain);
956 return c;
957 }
958
959 private native Class<?> defineClass0(String name, byte[] b, int off, int len,
960 ProtectionDomain pd);
961
962 private native Class<?> defineClass1(String name, byte[] b, int off, int len,
963 ProtectionDomain pd, String source);
964
965 private native Class<?> defineClass2(String name, java.nio.ByteBuffer b,
966 int off, int len, ProtectionDomain pd,
967 String source);
968
969 // true if the name is null or has the potential to be a valid binary name
970 private boolean checkName(String name) {
971 if ((name == null) || (name.length() == 0))
972 return true;
973 if ((name.indexOf('/') != -1)
974 || (!VM.allowArraySyntax() && (name.charAt(0) == '[')))
975 return false;
976 return true;
977 }
978
979 private void checkCerts(String name, CodeSource cs) {
980 int i = name.lastIndexOf('.');
981 String pname = (i == -1) ? "" : name.substring(0, i);
982
983 Certificate[] certs = null;
984 if (cs != null) {
985 certs = cs.getCertificates();
986 }
987 Certificate[] pcerts = null;
988 if (!isParallelCapable()) {
989 synchronized (this) {
990 pcerts = package2certs.get(pname);
991 if (pcerts == null) {
992 package2certs.put(pname, (certs == null? nocerts:certs));
993 }
994 }
995 } else {
996 pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
997 putIfAbsent(pname, (certs == null? nocerts:certs));
998 }
999 if (pcerts != null && !compareCerts(pcerts, certs)) {
1000 throw new SecurityException("class \""+ name +
1001 "\"'s signer information does not match signer information of other classes in the same package");
1002 }
1003 }
1004
1005 /**
1006 * check to make sure the certs for the new class (certs) are the same as
1007 * the certs for the first class inserted in the package (pcerts)
1008 */
1009 private boolean compareCerts(Certificate[] pcerts,
1010 Certificate[] certs)
1011 {
1012 // certs can be null, indicating no certs.
1013 if ((certs == null) || (certs.length == 0)) {
1014 return pcerts.length == 0;
1015 }
1016
1017 // the length must be the same at this point
1018 if (certs.length != pcerts.length)
1019 return false;
1020
1021 // go through and make sure all the certs in one array
1022 // are in the other and vice-versa.
1023 boolean match;
1024 for (int i = 0; i < certs.length; i++) {
1025 match = false;
1026 for (int j = 0; j < pcerts.length; j++) {
1027 if (certs[i].equals(pcerts[j])) {
1028 match = true;
1029 break;
1030 }
1031 }
1032 if (!match) return false;
1033 }
1034
1035 // now do the same for pcerts
1036 for (int i = 0; i < pcerts.length; i++) {
1037 match = false;
1038 for (int j = 0; j < certs.length; j++) {
1039 if (pcerts[i].equals(certs[j])) {
1040 match = true;
1041 break;
1042 }
1043 }
1044 if (!match) return false;
1045 }
1046
1047 return true;
1048 }
1049
1050 /**
1051 * Links the specified class. This (misleadingly named) method may be
1052 * used by a class loader to link a class. If the class <tt>c</tt> has
1053 * already been linked, then this method simply returns. Otherwise, the
1054 * class is linked as described in the "Execution" chapter of
1055 * <cite>The Java™ Language Specification</cite>.
1056 * </p>
1057 *
1058 * @param c
1059 * The class to link
1060 *
1061 * @throws NullPointerException
1062 * If <tt>c</tt> is <tt>null</tt>.
1063 *
1064 * @see #defineClass(String, byte[], int, int)
1065 */
1066 protected final void resolveClass(Class<?> c) {
1067 resolveClass0(c);
1068 }
1069
1070 private native void resolveClass0(Class<?> c);
1071
1072 /**
1073 * Finds a class with the specified <a href="#name">binary name</a>,
1074 * loading it if necessary.
1075 *
1076 * <p> This method loads the class through the system class loader (see
1077 * {@link #getSystemClassLoader()}). The <tt>Class</tt> object returned
1078 * might have more than one <tt>ClassLoader</tt> associated with it.
1079 * Subclasses of <tt>ClassLoader</tt> need not usually invoke this method,
1080 * because most class loaders need to override just {@link
1081 * #findClass(String)}. </p>
1082 *
1083 * @param name
1084 * The <a href="#name">binary name</a> of the class
1085 *
1086 * @return The <tt>Class</tt> object for the specified <tt>name</tt>
1087 *
1088 * @throws ClassNotFoundException
1089 * If the class could not be found
1090 *
1091 * @see #ClassLoader(ClassLoader)
1092 * @see #getParent()
1093 */
1094 protected final Class<?> findSystemClass(String name)
1095 throws ClassNotFoundException
1096 {
1097 ClassLoader system = getSystemClassLoader();
1098 if (system == null) {
1099 if (!checkName(name))
1100 throw new ClassNotFoundException(name);
1101 Class<?> cls = findBootstrapClass(name);
1102 if (cls == null) {
1103 throw new ClassNotFoundException(name);
1104 }
1105 return cls;
1106 }
1107 return system.loadClass(name);
1108 }
1109
1110 /**
1111 * Returns a class loaded by the bootstrap class loader;
1112 * or return null if not found.
1113 */
1114 private Class<?> findBootstrapClassOrNull(String name)
1115 {
1116 if (!checkName(name)) return null;
1117
1118 return findBootstrapClass(name);
1119 }
1120
1121 // return null if not found
1122 private native Class<?> findBootstrapClass(String name);
1123
1124 /**
1125 * Returns the class with the given <a href="#name">binary name</a> if this
1126 * loader has been recorded by the Java virtual machine as an initiating
1127 * loader of a class with that <a href="#name">binary name</a>. Otherwise
1128 * <tt>null</tt> is returned. </p>
1129 *
1130 * @param name
1131 * The <a href="#name">binary name</a> of the class
1132 *
1133 * @return The <tt>Class</tt> object, or <tt>null</tt> if the class has
1134 * not been loaded
1135 *
1136 * @since 1.1
1137 */
1138 protected final Class<?> findLoadedClass(String name) {
1139 if (!checkName(name))
1140 return null;
1141 return findLoadedClass0(name);
1142 }
1143
1144 private native final Class<?> findLoadedClass0(String name);
1145
1146 /**
1147 * Sets the signers of a class. This should be invoked after defining a
1148 * class. </p>
1149 *
1150 * @param c
1151 * The <tt>Class</tt> object
1152 *
1153 * @param signers
1154 * The signers for the class
1155 *
1156 * @since 1.1
1157 */
1158 protected final void setSigners(Class<?> c, Object[] signers) {
1159 c.setSigners(signers);
1160 }
1161
1162
1163 // -- Resource --
1164
1165 /**
1166 * Finds the resource with the given name. A resource is some data
1167 * (images, audio, text, etc) that can be accessed by class code in a way
1168 * that is independent of the location of the code.
1169 *
1170 * <p> The name of a resource is a '<tt>/</tt>'-separated path name that
1171 * identifies the resource.
1172 *
1173 * <p> This method will first search the parent class loader for the
1174 * resource; if the parent is <tt>null</tt> the path of the class loader
1175 * built-in to the virtual machine is searched. That failing, this method
1176 * will invoke {@link #findResource(String)} to find the resource. </p>
1177 *
1178 * @param name
1179 * The resource name
1180 *
1181 * @return A <tt>URL</tt> object for reading the resource, or
1182 * <tt>null</tt> if the resource could not be found or the invoker
1183 * doesn't have adequate privileges to get the resource.
1184 *
1185 * @since 1.1
1186 */
1187 public URL getResource(String name) {
1188 URL url;
1189 if (parent != null) {
1190 url = parent.getResource(name);
1191 } else {
1192 url = getBootstrapResource(name);
1193 }
1194 if (url == null) {
1195 url = findResource(name);
1196 }
1197 return url;
1198 }
1199
1200 /**
1201 * Finds all the resources with the given name. A resource is some data
1202 * (images, audio, text, etc) that can be accessed by class code in a way
1203 * that is independent of the location of the code.
1204 *
1205 * <p>The name of a resource is a <tt>/</tt>-separated path name that
1206 * identifies the resource.
1207 *
1208 * <p> The search order is described in the documentation for {@link
1209 * #getResource(String)}. </p>
1210 *
1211 * @param name
1212 * The resource name
1213 *
1214 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1215 * the resource. If no resources could be found, the enumeration
1216 * will be empty. Resources that the class loader doesn't have
1217 * access to will not be in the enumeration.
1218 *
1219 * @throws IOException
1220 * If I/O errors occur
1221 *
1222 * @see #findResources(String)
1223 *
1224 * @since 1.2
1225 */
1226 public Enumeration<URL> getResources(String name) throws IOException {
1227 @SuppressWarnings("unchecked")
1228 Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
1229 if (parent != null) {
1230 tmp[0] = parent.getResources(name);
1231 } else {
1232 tmp[0] = getBootstrapResources(name);
1233 }
1234 tmp[1] = findResources(name);
1235
1236 return new CompoundEnumeration<>(tmp);
1237 }
1238
1239 /**
1240 * Finds the resource with the given name. Class loader implementations
1241 * should override this method to specify where to find resources. </p>
1242 *
1243 * @param name
1244 * The resource name
1245 *
1246 * @return A <tt>URL</tt> object for reading the resource, or
1247 * <tt>null</tt> if the resource could not be found
1248 *
1249 * @since 1.2
1250 */
1251 protected URL findResource(String name) {
1252 return null;
1253 }
1254
1255 /**
1256 * Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
1257 * representing all the resources with the given name. Class loader
1258 * implementations should override this method to specify where to load
1259 * resources from. </p>
1260 *
1261 * @param name
1262 * The resource name
1263 *
1264 * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
1265 * the resources
1266 *
1267 * @throws IOException
1268 * If I/O errors occur
1269 *
1270 * @since 1.2
1271 */
1272 protected Enumeration<URL> findResources(String name) throws IOException {
1273 return java.util.Collections.emptyEnumeration();
1274 }
1275
1276 // index 0: java.lang.ClassLoader.class
1277 // index 1: the immediate caller of index 0.
1278 // index 2: the immediate caller of index 1.
1279 private static native Class<? extends ClassLoader> getCaller(int index);
1280
1281 /**
1282 * Registers the caller as parallel capable.</p>
1283 * The registration succeeds if and only if all of the following
1284 * conditions are met: <br>
1285 * 1. no instance of the caller has been created</p>
1286 * 2. all of the super classes (except class Object) of the caller are
1287 * registered as parallel capable</p>
1288 * Note that once a class loader is registered as parallel capable, there
1289 * is no way to change it back. </p>
1290 * <p>
1291 * Class loaders that are fully concurrent parallel capable should
1292 * use {@link #registerAsFullyConcurrent} to register. </p>
1293 *
1294 * @return true if the caller is successfully registered as
1295 * parallel capable and false if otherwise.
1296 *
1297 * @since 1.7
1298 */
1299 protected static boolean registerAsParallelCapable() {
1300 return ParallelLoaders.register(getCaller(1), false);
1301 }
1302
1303 /**
1304 * Registers the caller as a fully concurrent parallel capable
1305 * class loader.</p>
1306 * The registration succeeds if and only if all of the following
1307 * conditions are met: <br>
1308 * 1. no instance of the caller has been created</p>
1309 * 2. all of the super classes (except class Object) of the caller are
1310 * registered as parallel capable</p>
1311 * Note that once a class loader is registered as fully concurrent
1312 * parallel capable, there is no way to change it back. </p>
1313 *
1314 * @return true if the caller is successfully registered as
1315 * fully concurrent parallel capable and false if otherwise.
1316 *
1317 * @since 1.8
1318 */
1319 protected static boolean registerAsFullyConcurrent() {
1320 return ParallelLoaders.register(getCaller(1), true);
1321 }
1322
1323 /**
1324 * Find a resource of the specified name from the search path used to load
1325 * classes. This method locates the resource through the system class
1326 * loader (see {@link #getSystemClassLoader()}). </p>
1327 *
1328 * @param name
1329 * The resource name
1330 *
1331 * @return A {@link java.net.URL <tt>URL</tt>} object for reading the
1332 * resource, or <tt>null</tt> if the resource could not be found
1333 *
1334 * @since 1.1
1335 */
1336 public static URL getSystemResource(String name) {
1337 ClassLoader system = getSystemClassLoader();
1338 if (system == null) {
1339 return getBootstrapResource(name);
1340 }
1341 return system.getResource(name);
1342 }
1343
1344 /**
1345 * Finds all resources of the specified name from the search path used to
1346 * load classes. The resources thus found are returned as an
1347 * {@link java.util.Enumeration <tt>Enumeration</tt>} of {@link
1348 * java.net.URL <tt>URL</tt>} objects.
1349 *
1350 * <p> The search order is described in the documentation for {@link
1351 * #getSystemResource(String)}. </p>
1352 *
1353 * @param name
1354 * The resource name
1355 *
1356 * @return An enumeration of resource {@link java.net.URL <tt>URL</tt>}
1357 * objects
1358 *
1359 * @throws IOException
1360 * If I/O errors occur
1361
1362 * @since 1.2
1363 */
1364 public static Enumeration<URL> getSystemResources(String name)
1365 throws IOException
1366 {
1367 ClassLoader system = getSystemClassLoader();
1368 if (system == null) {
1369 return getBootstrapResources(name);
1370 }
1371 return system.getResources(name);
1372 }
1373
1374 /**
1375 * Find resources from the VM's built-in classloader.
1376 */
1377 private static URL getBootstrapResource(String name) {
1378 URLClassPath ucp = getBootstrapClassPath();
1379 Resource res = ucp.getResource(name);
1380 return res != null ? res.getURL() : null;
1381 }
1382
1383 /**
1384 * Find resources from the VM's built-in classloader.
1385 */
1386 private static Enumeration<URL> getBootstrapResources(String name)
1387 throws IOException
1388 {
1389 final Enumeration<Resource> e =
1390 getBootstrapClassPath().getResources(name);
1391 return new Enumeration<URL> () {
1392 public URL nextElement() {
1393 return e.nextElement().getURL();
1394 }
1395 public boolean hasMoreElements() {
1396 return e.hasMoreElements();
1397 }
1398 };
1399 }
1400
1401 // Returns the URLClassPath that is used for finding system resources.
1402 static URLClassPath getBootstrapClassPath() {
1403 return sun.misc.Launcher.getBootstrapClassPath();
1404 }
1405
1406
1407 /**
1408 * Returns an input stream for reading the specified resource.
1409 *
1410 * <p> The search order is described in the documentation for {@link
1411 * #getResource(String)}. </p>
1412 *
1413 * @param name
1414 * The resource name
1415 *
1416 * @return An input stream for reading the resource, or <tt>null</tt>
1417 * if the resource could not be found
1418 *
1419 * @since 1.1
1420 */
1421 public InputStream getResourceAsStream(String name) {
1422 URL url = getResource(name);
1423 try {
1424 return url != null ? url.openStream() : null;
1425 } catch (IOException e) {
1426 return null;
1427 }
1428 }
1429
1430 /**
1431 * Open for reading, a resource of the specified name from the search path
1432 * used to load classes. This method locates the resource through the
1433 * system class loader (see {@link #getSystemClassLoader()}). </p>
1434 *
1435 * @param name
1436 * The resource name
1437 *
1438 * @return An input stream for reading the resource, or <tt>null</tt>
1439 * if the resource could not be found
1440 *
1441 * @since 1.1
1442 */
1443 public static InputStream getSystemResourceAsStream(String name) {
1444 URL url = getSystemResource(name);
1445 try {
1446 return url != null ? url.openStream() : null;
1447 } catch (IOException e) {
1448 return null;
1449 }
1450 }
1451
1452
1453 // -- Hierarchy --
1454
1455 /**
1456 * Returns the parent class loader for delegation. Some implementations may
1457 * use <tt>null</tt> to represent the bootstrap class loader. This method
1458 * will return <tt>null</tt> in such implementations if this class loader's
1459 * parent is the bootstrap class loader.
1460 *
1461 * <p> If a security manager is present, and the invoker's class loader is
1462 * not <tt>null</tt> and is not an ancestor of this class loader, then this
1463 * method invokes the security manager's {@link
1464 * SecurityManager#checkPermission(java.security.Permission)
1465 * <tt>checkPermission</tt>} method with a {@link
1466 * RuntimePermission#RuntimePermission(String)
1467 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1468 * access to the parent class loader is permitted. If not, a
1469 * <tt>SecurityException</tt> will be thrown. </p>
1470 *
1471 * @return The parent <tt>ClassLoader</tt>
1472 *
1473 * @throws SecurityException
1474 * If a security manager exists and its <tt>checkPermission</tt>
1475 * method doesn't allow access to this class loader's parent class
1476 * loader.
1477 *
1478 * @since 1.2
1479 */
1480 public final ClassLoader getParent() {
1481 if (parent == null)
1482 return null;
1483 SecurityManager sm = System.getSecurityManager();
1484 if (sm != null) {
1485 ClassLoader ccl = getCallerClassLoader();
1486 if (needsClassLoaderPermissionCheck(ccl, this)) {
1487 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1488 }
1489 }
1490 return parent;
1491 }
1492
1493 /**
1494 * Returns the system class loader for delegation. This is the default
1495 * delegation parent for new <tt>ClassLoader</tt> instances, and is
1496 * typically the class loader used to start the application.
1497 *
1498 * <p> This method is first invoked early in the runtime's startup
1499 * sequence, at which point it creates the system class loader and sets it
1500 * as the context class loader of the invoking <tt>Thread</tt>.
1501 *
1502 * <p> The default system class loader is an implementation-dependent
1503 * instance of this class.
1504 *
1505 * <p> If the system property "<tt>java.system.class.loader</tt>" is defined
1506 * when this method is first invoked then the value of that property is
1507 * taken to be the name of a class that will be returned as the system
1508 * class loader. The class is loaded using the default system class loader
1509 * and must define a public constructor that takes a single parameter of
1510 * type <tt>ClassLoader</tt> which is used as the delegation parent. An
1511 * instance is then created using this constructor with the default system
1512 * class loader as the parameter. The resulting class loader is defined
1513 * to be the system class loader.
1514 *
1515 * <p> If a security manager is present, and the invoker's class loader is
1516 * not <tt>null</tt> and the invoker's class loader is not the same as or
1517 * an ancestor of the system class loader, then this method invokes the
1518 * security manager's {@link
1519 * SecurityManager#checkPermission(java.security.Permission)
1520 * <tt>checkPermission</tt>} method with a {@link
1521 * RuntimePermission#RuntimePermission(String)
1522 * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
1523 * access to the system class loader. If not, a
1524 * <tt>SecurityException</tt> will be thrown. </p>
1525 *
1526 * @return The system <tt>ClassLoader</tt> for delegation, or
1527 * <tt>null</tt> if none
1528 *
1529 * @throws SecurityException
1530 * If a security manager exists and its <tt>checkPermission</tt>
1531 * method doesn't allow access to the system class loader.
1532 *
1533 * @throws IllegalStateException
1534 * If invoked recursively during the construction of the class
1535 * loader specified by the "<tt>java.system.class.loader</tt>"
1536 * property.
1537 *
1538 * @throws Error
1539 * If the system property "<tt>java.system.class.loader</tt>"
1540 * is defined but the named class could not be loaded, the
1541 * provider class does not define the required constructor, or an
1542 * exception is thrown by that constructor when it is invoked. The
1543 * underlying cause of the error can be retrieved via the
1544 * {@link Throwable#getCause()} method.
1545 *
1546 * @revised 1.4
1547 */
1548 public static ClassLoader getSystemClassLoader() {
1549 initSystemClassLoader();
1550 if (scl == null) {
1551 return null;
1552 }
1553 SecurityManager sm = System.getSecurityManager();
1554 if (sm != null) {
1555 ClassLoader ccl = getCallerClassLoader();
1556 if (needsClassLoaderPermissionCheck(ccl, scl)) {
1557 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1558 }
1559 }
1560 return scl;
1561 }
1562
1563 private static synchronized void initSystemClassLoader() {
1564 if (!sclSet) {
1565 if (scl != null)
1566 throw new IllegalStateException("recursive invocation");
1567 sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
1568 if (l != null) {
1569 Throwable oops = null;
1570 scl = l.getClassLoader();
1571 try {
1572 scl = AccessController.doPrivileged(
1573 new SystemClassLoaderAction(scl));
1574 } catch (PrivilegedActionException pae) {
1575 oops = pae.getCause();
1576 if (oops instanceof InvocationTargetException) {
1577 oops = oops.getCause();
1578 }
1579 }
1580 if (oops != null) {
1581 if (oops instanceof Error) {
1582 throw (Error) oops;
1583 } else {
1584 // wrap the exception
1585 throw new Error(oops);
1586 }
1587 }
1588 }
1589 sclSet = true;
1590 }
1591 }
1592
1593 // Returns true if the specified class loader can be found in this class
1594 // loader's delegation chain.
1595 boolean isAncestor(ClassLoader cl) {
1596 ClassLoader acl = this;
1597 do {
1598 acl = acl.parent;
1599 if (cl == acl) {
1600 return true;
1601 }
1602 } while (acl != null);
1603 return false;
1604 }
1605
1606 // Tests if class loader access requires "getClassLoader" permission
1607 // check. A class loader 'from' can access class loader 'to' if
1608 // class loader 'from' is same as class loader 'to' or an ancestor
1609 // of 'to'. The class loader in a system domain can access
1610 // any class loader.
1611 static boolean needsClassLoaderPermissionCheck(ClassLoader from,
1612 ClassLoader to)
1613 {
1614 if (from == to)
1615 return false;
1616
1617 if (from == null)
1618 return false;
1619
1620 return !to.isAncestor(from);
1621 }
1622
1623 // Returns the invoker's class loader, or null if none.
1624 // NOTE: This must always be invoked when there is exactly one intervening
1625 // frame from the core libraries on the stack between this method's
1626 // invocation and the desired invoker.
1627 static ClassLoader getCallerClassLoader() {
1628 // NOTE use of more generic Reflection.getCallerClass()
1629 Class<?> caller = Reflection.getCallerClass(3);
1630 // This can be null if the VM is requesting it
1631 if (caller == null) {
1632 return null;
1633 }
1634 // Circumvent security check since this is package-private
1635 return caller.getClassLoader0();
1636 }
1637
1638 // The class loader for the system
1639 // @GuardedBy("ClassLoader.class")
1640 private static ClassLoader scl;
1641
1642 // Set to true once the system class loader has been set
1643 // @GuardedBy("ClassLoader.class")
1644 private static boolean sclSet;
1645
1646
1647 // -- Package --
1648
1649 /**
1650 * Defines a package by name in this <tt>ClassLoader</tt>. This allows
1651 * class loaders to define the packages for their classes. Packages must
1652 * be created before the class is defined, and package names must be
1653 * unique within a class loader and cannot be redefined or changed once
1654 * created. </p>
1655 *
1656 * @param name
1657 * The package name
1658 *
1659 * @param specTitle
1660 * The specification title
1661 *
1662 * @param specVersion
1663 * The specification version
1664 *
1665 * @param specVendor
1666 * The specification vendor
1667 *
1668 * @param implTitle
1669 * The implementation title
1670 *
1671 * @param implVersion
1672 * The implementation version
1673 *
1674 * @param implVendor
1675 * The implementation vendor
1676 *
1677 * @param sealBase
1678 * If not <tt>null</tt>, then this package is sealed with
1679 * respect to the given code source {@link java.net.URL
1680 * <tt>URL</tt>} object. Otherwise, the package is not sealed.
1681 *
1682 * @return The newly defined <tt>Package</tt> object
1683 *
1684 * @throws IllegalArgumentException
1685 * If package name duplicates an existing package either in this
1686 * class loader or one of its ancestors
1687 *
1688 * @since 1.2
1689 */
1690 protected Package definePackage(String name, String specTitle,
1691 String specVersion, String specVendor,
1692 String implTitle, String implVersion,
1693 String implVendor, URL sealBase)
1694 throws IllegalArgumentException
1695 {
1696 synchronized (packages) {
1697 Package pkg = getPackage(name);
1698 if (pkg != null) {
1699 throw new IllegalArgumentException(name);
1700 }
1701 pkg = new Package(name, specTitle, specVersion, specVendor,
1702 implTitle, implVersion, implVendor,
1703 sealBase, this);
1704 packages.put(name, pkg);
1705 return pkg;
1706 }
1707 }
1708
1709 /**
1710 * Returns a <tt>Package</tt> that has been defined by this class loader
1711 * or any of its ancestors. </p>
1712 *
1713 * @param name
1714 * The package name
1715 *
1716 * @return The <tt>Package</tt> corresponding to the given name, or
1717 * <tt>null</tt> if not found
1718 *
1719 * @since 1.2
1720 */
1721 protected Package getPackage(String name) {
1722 Package pkg;
1723 synchronized (packages) {
1724 pkg = packages.get(name);
1725 }
1726 if (pkg == null) {
1727 if (parent != null) {
1728 pkg = parent.getPackage(name);
1729 } else {
1730 pkg = Package.getSystemPackage(name);
1731 }
1732 if (pkg != null) {
1733 synchronized (packages) {
1734 Package pkg2 = packages.get(name);
1735 if (pkg2 == null) {
1736 packages.put(name, pkg);
1737 } else {
1738 pkg = pkg2;
1739 }
1740 }
1741 }
1742 }
1743 return pkg;
1744 }
1745
1746 /**
1747 * Returns all of the <tt>Packages</tt> defined by this class loader and
1748 * its ancestors. </p>
1749 *
1750 * @return The array of <tt>Package</tt> objects defined by this
1751 * <tt>ClassLoader</tt>
1752 *
1753 * @since 1.2
1754 */
1755 protected Package[] getPackages() {
1756 Map<String, Package> map;
1757 synchronized (packages) {
1758 map = new HashMap<>(packages);
1759 }
1760 Package[] pkgs;
1761 if (parent != null) {
1762 pkgs = parent.getPackages();
1763 } else {
1764 pkgs = Package.getSystemPackages();
1765 }
1766 if (pkgs != null) {
1767 for (int i = 0; i < pkgs.length; i++) {
1768 String pkgName = pkgs[i].getName();
1769 if (map.get(pkgName) == null) {
1770 map.put(pkgName, pkgs[i]);
1771 }
1772 }
1773 }
1774 return map.values().toArray(new Package[map.size()]);
1775 }
1776
1777
1778 // -- Native library access --
1779
1780 /**
1781 * Returns the absolute path name of a native library. The VM invokes this
1782 * method to locate the native libraries that belong to classes loaded with
1783 * this class loader. If this method returns <tt>null</tt>, the VM
1784 * searches the library along the path specified as the
1785 * "<tt>java.library.path</tt>" property. </p>
1786 *
1787 * @param libname
1788 * The library name
1789 *
1790 * @return The absolute path of the native library
1791 *
1792 * @see System#loadLibrary(String)
1793 * @see System#mapLibraryName(String)
1794 *
1795 * @since 1.2
1796 */
1797 protected String findLibrary(String libname) {
1798 return null;
1799 }
1800
1801 /**
1802 * The inner class NativeLibrary denotes a loaded native library instance.
1803 * Every classloader contains a vector of loaded native libraries in the
1804 * private field <tt>nativeLibraries</tt>. The native libraries loaded
1805 * into the system are entered into the <tt>systemNativeLibraries</tt>
1806 * vector.
1807 *
1808 * <p> Every native library requires a particular version of JNI. This is
1809 * denoted by the private <tt>jniVersion</tt> field. This field is set by
1810 * the VM when it loads the library, and used by the VM to pass the correct
1811 * version of JNI to the native methods. </p>
1812 *
1813 * @see ClassLoader
1814 * @since 1.2
1815 */
1816 static class NativeLibrary {
1817 // opaque handle to native library, used in native code.
1818 long handle;
1819 // the version of JNI environment the native library requires.
1820 private int jniVersion;
1821 // the class from which the library is loaded, also indicates
1822 // the loader this native library belongs.
1823 private Class<?> fromClass;
1824 // the canonicalized name of the native library.
1825 String name;
1826
1827 native void load(String name);
1828 native long find(String name);
1829 native void unload();
1830
1831 public NativeLibrary(Class<?> fromClass, String name) {
1832 this.name = name;
1833 this.fromClass = fromClass;
1834 }
1835
1836 protected void finalize() {
1837 synchronized (loadedLibraryNames) {
1838 if (fromClass.getClassLoader() != null && handle != 0) {
1839 /* remove the native library name */
1840 int size = loadedLibraryNames.size();
1841 for (int i = 0; i < size; i++) {
1842 if (name.equals(loadedLibraryNames.elementAt(i))) {
1843 loadedLibraryNames.removeElementAt(i);
1844 break;
1845 }
1846 }
1847 /* unload the library. */
1848 ClassLoader.nativeLibraryContext.push(this);
1849 try {
1850 unload();
1851 } finally {
1852 ClassLoader.nativeLibraryContext.pop();
1853 }
1854 }
1855 }
1856 }
1857 // Invoked in the VM to determine the context class in
1858 // JNI_Load/JNI_Unload
1859 static Class<?> getFromClass() {
1860 return ClassLoader.nativeLibraryContext.peek().fromClass;
1861 }
1862 }
1863
1864 // All native library names we've loaded.
1865 private static Vector<String> loadedLibraryNames = new Vector<>();
1866
1867 // Native libraries belonging to system classes.
1868 private static Vector<NativeLibrary> systemNativeLibraries
1869 = new Vector<>();
1870
1871 // Native libraries associated with the class loader.
1872 private Vector<NativeLibrary> nativeLibraries = new Vector<>();
1873
1874 // native libraries being loaded/unloaded.
1875 private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>();
1876
1877 // The paths searched for libraries
1878 private static String usr_paths[];
1879 private static String sys_paths[];
1880
1881 private static String[] initializePath(String propname) {
1882 String ldpath = System.getProperty(propname, "");
1883 String ps = File.pathSeparator;
1884 int ldlen = ldpath.length();
1885 int i, j, n;
1886 // Count the separators in the path
1887 i = ldpath.indexOf(ps);
1888 n = 0;
1889 while (i >= 0) {
1890 n++;
1891 i = ldpath.indexOf(ps, i + 1);
1892 }
1893
1894 // allocate the array of paths - n :'s = n + 1 path elements
1895 String[] paths = new String[n + 1];
1896
1897 // Fill the array with paths from the ldpath
1898 n = i = 0;
1899 j = ldpath.indexOf(ps);
1900 while (j >= 0) {
1901 if (j - i > 0) {
1902 paths[n++] = ldpath.substring(i, j);
1903 } else if (j - i == 0) {
1904 paths[n++] = ".";
1905 }
1906 i = j + 1;
1907 j = ldpath.indexOf(ps, i);
1908 }
1909 paths[n] = ldpath.substring(i, ldlen);
1910 return paths;
1911 }
1912
1913 // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
1914 static void loadLibrary(Class<?> fromClass, String name,
1915 boolean isAbsolute) {
1916 ClassLoader loader =
1917 (fromClass == null) ? null : fromClass.getClassLoader();
1918 if (sys_paths == null) {
1919 usr_paths = initializePath("java.library.path");
1920 sys_paths = initializePath("sun.boot.library.path");
1921 }
1922 if (isAbsolute) {
1923 if (loadLibrary0(fromClass, new File(name))) {
1924 return;
1925 }
1926 throw new UnsatisfiedLinkError("Can't load library: " + name);
1927 }
1928 if (loader != null) {
1929 String libfilename = loader.findLibrary(name);
1930 if (libfilename != null) {
1931 File libfile = new File(libfilename);
1932 if (!libfile.isAbsolute()) {
1933 throw new UnsatisfiedLinkError(
1934 "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
1935 }
1936 if (loadLibrary0(fromClass, libfile)) {
1937 return;
1938 }
1939 throw new UnsatisfiedLinkError("Can't load " + libfilename);
1940 }
1941 }
1942 for (int i = 0 ; i < sys_paths.length ; i++) {
1943 File libfile = new File(sys_paths[i], System.mapLibraryName(name));
1944 if (loadLibrary0(fromClass, libfile)) {
1945 return;
1946 }
1947 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
1948 if (libfile != null && loadLibrary0(fromClass, libfile)) {
1949 return;
1950 }
1951 }
1952 if (loader != null) {
1953 for (int i = 0 ; i < usr_paths.length ; i++) {
1954 File libfile = new File(usr_paths[i],
1955 System.mapLibraryName(name));
1956 if (loadLibrary0(fromClass, libfile)) {
1957 return;
1958 }
1959 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
1960 if (libfile != null && loadLibrary0(fromClass, libfile)) {
1961 return;
1962 }
1963 }
1964 }
1965 // Oops, it failed
1966 throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
1967 }
1968
1969 private static boolean loadLibrary0(Class<?> fromClass, final File file) {
1970 boolean exists = AccessController.doPrivileged(
1971 new PrivilegedAction<Object>() {
1972 public Object run() {
1973 return file.exists() ? Boolean.TRUE : null;
1974 }})
1975 != null;
1976 if (!exists) {
1977 return false;
1978 }
1979 String name;
1980 try {
1981 name = file.getCanonicalPath();
1982 } catch (IOException e) {
1983 return false;
1984 }
1985 ClassLoader loader =
1986 (fromClass == null) ? null : fromClass.getClassLoader();
1987 Vector<NativeLibrary> libs =
1988 loader != null ? loader.nativeLibraries : systemNativeLibraries;
1989 synchronized (libs) {
1990 int size = libs.size();
1991 for (int i = 0; i < size; i++) {
1992 NativeLibrary lib = libs.elementAt(i);
1993 if (name.equals(lib.name)) {
1994 return true;
1995 }
1996 }
1997
1998 synchronized (loadedLibraryNames) {
1999 if (loadedLibraryNames.contains(name)) {
2000 throw new UnsatisfiedLinkError
2001 ("Native Library " +
2002 name +
2003 " already loaded in another classloader");
2004 }
2005 /* If the library is being loaded (must be by the same thread,
2006 * because Runtime.load and Runtime.loadLibrary are
2007 * synchronous). The reason is can occur is that the JNI_OnLoad
2008 * function can cause another loadLibrary invocation.
2009 *
2010 * Thus we can use a static stack to hold the list of libraries
2011 * we are loading.
2012 *
2013 * If there is a pending load operation for the library, we
2014 * immediately return success; otherwise, we raise
2015 * UnsatisfiedLinkError.
2016 */
2017 int n = nativeLibraryContext.size();
2018 for (int i = 0; i < n; i++) {
2019 NativeLibrary lib = nativeLibraryContext.elementAt(i);
2020 if (name.equals(lib.name)) {
2021 if (loader == lib.fromClass.getClassLoader()) {
2022 return true;
2023 } else {
2024 throw new UnsatisfiedLinkError
2025 ("Native Library " +
2026 name +
2027 " is being loaded in another classloader");
2028 }
2029 }
2030 }
2031 NativeLibrary lib = new NativeLibrary(fromClass, name);
2032 nativeLibraryContext.push(lib);
2033 try {
2034 lib.load(name);
2035 } finally {
2036 nativeLibraryContext.pop();
2037 }
2038 if (lib.handle != 0) {
2039 loadedLibraryNames.addElement(name);
2040 libs.addElement(lib);
2041 return true;
2042 }
2043 return false;
2044 }
2045 }
2046 }
2047
2048 // Invoked in the VM class linking code.
2049 static long findNative(ClassLoader loader, String name) {
2050 Vector<NativeLibrary> libs =
2051 loader != null ? loader.nativeLibraries : systemNativeLibraries;
2052 synchronized (libs) {
2053 int size = libs.size();
2054 for (int i = 0; i < size; i++) {
2055 NativeLibrary lib = libs.elementAt(i);
2056 long entry = lib.find(name);
2057 if (entry != 0)
2058 return entry;
2059 }
2060 }
2061 return 0;
2062 }
2063
2064
2065 // -- Assertion management --
2066
2067 final Object assertionLock;
2068
2069 // The default toggle for assertion checking.
2070 // @GuardedBy("assertionLock")
2071 private boolean defaultAssertionStatus = false;
2072
2073 // Maps String packageName to Boolean package default assertion status Note
2074 // that the default package is placed under a null map key. If this field
2075 // is null then we are delegating assertion status queries to the VM, i.e.,
2076 // none of this ClassLoader's assertion status modification methods have
2077 // been invoked.
2078 // @GuardedBy("assertionLock")
2079 private Map<String, Boolean> packageAssertionStatus = null;
2080
2081 // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
2082 // field is null then we are delegating assertion status queries to the VM,
2083 // i.e., none of this ClassLoader's assertion status modification methods
2084 // have been invoked.
2085 // @GuardedBy("assertionLock")
2086 Map<String, Boolean> classAssertionStatus = null;
2087
2088 /**
2089 * Sets the default assertion status for this class loader. This setting
2090 * determines whether classes loaded by this class loader and initialized
2091 * in the future will have assertions enabled or disabled by default.
2092 * This setting may be overridden on a per-package or per-class basis by
2093 * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
2094 * #setClassAssertionStatus(String, boolean)}. </p>
2095 *
2096 * @param enabled
2097 * <tt>true</tt> if classes loaded by this class loader will
2098 * henceforth have assertions enabled by default, <tt>false</tt>
2099 * if they will have assertions disabled by default.
2100 *
2101 * @since 1.4
2102 */
2103 public void setDefaultAssertionStatus(boolean enabled) {
2104 synchronized (assertionLock) {
2105 if (classAssertionStatus == null)
2106 initializeJavaAssertionMaps();
2107
2108 defaultAssertionStatus = enabled;
2109 }
2110 }
2111
2112 /**
2113 * Sets the package default assertion status for the named package. The
2114 * package default assertion status determines the assertion status for
2115 * classes initialized in the future that belong to the named package or
2116 * any of its "subpackages".
2117 *
2118 * <p> A subpackage of a package named p is any package whose name begins
2119 * with "<tt>p.</tt>". For example, <tt>javax.swing.text</tt> is a
2120 * subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt> and
2121 * <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
2122 *
2123 * <p> In the event that multiple package defaults apply to a given class,
2124 * the package default pertaining to the most specific package takes
2125 * precedence over the others. For example, if <tt>javax.lang</tt> and
2126 * <tt>javax.lang.reflect</tt> both have package defaults associated with
2127 * them, the latter package default applies to classes in
2128 * <tt>javax.lang.reflect</tt>.
2129 *
2130 * <p> Package defaults take precedence over the class loader's default
2131 * assertion status, and may be overridden on a per-class basis by invoking
2132 * {@link #setClassAssertionStatus(String, boolean)}. </p>
2133 *
2134 * @param packageName
2135 * The name of the package whose package default assertion status
2136 * is to be set. A <tt>null</tt> value indicates the unnamed
2137 * package that is "current"
2138 * (see section 7.4.2 of
2139 * <cite>The Java™ Language Specification</cite>.)
2140 *
2141 * @param enabled
2142 * <tt>true</tt> if classes loaded by this classloader and
2143 * belonging to the named package or any of its subpackages will
2144 * have assertions enabled by default, <tt>false</tt> if they will
2145 * have assertions disabled by default.
2146 *
2147 * @since 1.4
2148 */
2149 public void setPackageAssertionStatus(String packageName,
2150 boolean enabled) {
2151 synchronized (assertionLock) {
2152 if (packageAssertionStatus == null)
2153 initializeJavaAssertionMaps();
2154
2155 packageAssertionStatus.put(packageName, enabled);
2156 }
2157 }
2158
2159 /**
2160 * Sets the desired assertion status for the named top-level class in this
2161 * class loader and any nested classes contained therein. This setting
2162 * takes precedence over the class loader's default assertion status, and
2163 * over any applicable per-package default. This method has no effect if
2164 * the named class has already been initialized. (Once a class is
2165 * initialized, its assertion status cannot change.)
2166 *
2167 * <p> If the named class is not a top-level class, this invocation will
2168 * have no effect on the actual assertion status of any class. </p>
2169 *
2170 * @param className
2171 * The fully qualified class name of the top-level class whose
2172 * assertion status is to be set.
2173 *
2174 * @param enabled
2175 * <tt>true</tt> if the named class is to have assertions
2176 * enabled when (and if) it is initialized, <tt>false</tt> if the
2177 * class is to have assertions disabled.
2178 *
2179 * @since 1.4
2180 */
2181 public void setClassAssertionStatus(String className, boolean enabled) {
2182 synchronized (assertionLock) {
2183 if (classAssertionStatus == null)
2184 initializeJavaAssertionMaps();
2185
2186 classAssertionStatus.put(className, enabled);
2187 }
2188 }
2189
2190 /**
2191 * Sets the default assertion status for this class loader to
2192 * <tt>false</tt> and discards any package defaults or class assertion
2193 * status settings associated with the class loader. This method is
2194 * provided so that class loaders can be made to ignore any command line or
2195 * persistent assertion status settings and "start with a clean slate."
2196 * </p>
2197 *
2198 * @since 1.4
2199 */
2200 public void clearAssertionStatus() {
2201 /*
2202 * Whether or not "Java assertion maps" are initialized, set
2203 * them to empty maps, effectively ignoring any present settings.
2204 */
2205 synchronized (assertionLock) {
2206 classAssertionStatus = new HashMap<>();
2207 packageAssertionStatus = new HashMap<>();
2208 defaultAssertionStatus = false;
2209 }
2210 }
2211
2212 /**
2213 * Returns the assertion status that would be assigned to the specified
2214 * class if it were to be initialized at the time this method is invoked.
2215 * If the named class has had its assertion status set, the most recent
2216 * setting will be returned; otherwise, if any package default assertion
2217 * status pertains to this class, the most recent setting for the most
2218 * specific pertinent package default assertion status is returned;
2219 * otherwise, this class loader's default assertion status is returned.
2220 * </p>
2221 *
2222 * @param className
2223 * The fully qualified class name of the class whose desired
2224 * assertion status is being queried.
2225 *
2226 * @return The desired assertion status of the specified class.
2227 *
2228 * @see #setClassAssertionStatus(String, boolean)
2229 * @see #setPackageAssertionStatus(String, boolean)
2230 * @see #setDefaultAssertionStatus(boolean)
2231 *
2232 * @since 1.4
2233 */
2234 boolean desiredAssertionStatus(String className) {
2235 synchronized (assertionLock) {
2236 // assert classAssertionStatus != null;
2237 // assert packageAssertionStatus != null;
2238
2239 // Check for a class entry
2240 Boolean result = classAssertionStatus.get(className);
2241 if (result != null)
2242 return result.booleanValue();
2243
2244 // Check for most specific package entry
2245 int dotIndex = className.lastIndexOf(".");
2246 if (dotIndex < 0) { // default package
2247 result = packageAssertionStatus.get(null);
2248 if (result != null)
2249 return result.booleanValue();
2250 }
2251 while(dotIndex > 0) {
2252 className = className.substring(0, dotIndex);
2253 result = packageAssertionStatus.get(className);
2254 if (result != null)
2255 return result.booleanValue();
2256 dotIndex = className.lastIndexOf(".", dotIndex-1);
2257 }
2258
2259 // Return the classloader default
2260 return defaultAssertionStatus;
2261 }
2262 }
2263
2264 // Set up the assertions with information provided by the VM.
2265 // Note: Should only be called inside a synchronized block
2266 private void initializeJavaAssertionMaps() {
2267 // assert Thread.holdsLock(assertionLock);
2268
2269 classAssertionStatus = new HashMap<>();
2270 packageAssertionStatus = new HashMap<>();
2271 AssertionStatusDirectives directives = retrieveDirectives();
2272
2273 for(int i = 0; i < directives.classes.length; i++)
2274 classAssertionStatus.put(directives.classes[i],
2275 directives.classEnabled[i]);
2276
2277 for(int i = 0; i < directives.packages.length; i++)
2278 packageAssertionStatus.put(directives.packages[i],
2279 directives.packageEnabled[i]);
2280
2281 defaultAssertionStatus = directives.deflt;
2282 }
2283
2284 // Retrieves the assertion directives from the VM.
2285 private static native AssertionStatusDirectives retrieveDirectives();
2286 }
2287
2288
2289 class SystemClassLoaderAction
2290 implements PrivilegedExceptionAction<ClassLoader> {
2291 private ClassLoader parent;
2292
2293 SystemClassLoaderAction(ClassLoader parent) {
2294 this.parent = parent;
2295 }
2296
2297 public ClassLoader run() throws Exception {
2298 String cls = System.getProperty("java.system.class.loader");
2299 if (cls == null) {
2300 return parent;
2301 }
2302
2303 Constructor<?> ctor = Class.forName(cls, true, parent)
2304 .getDeclaredConstructor(new Class<?>[] { ClassLoader.class });
2305 ClassLoader sys = (ClassLoader) ctor.newInstance(
2306 new Object[] { parent });
2307 Thread.currentThread().setContextClassLoader(sys);
2308 return sys;
2309 }
2310 }