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