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Diffstat (limited to 'libjava/java/lang/ClassLoader.java')
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diff --git a/libjava/java/lang/ClassLoader.java b/libjava/java/lang/ClassLoader.java deleted file mode 100644 index d555730..0000000 --- a/libjava/java/lang/ClassLoader.java +++ /dev/null @@ -1,1144 +0,0 @@ -/* ClassLoader.java -- responsible for loading classes into the VM - Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. - -This file is part of GNU Classpath. - -GNU Classpath is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -GNU Classpath is distributed in the hope that it will be useful, but -WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -General Public License for more details. - -You should have received a copy of the GNU General Public License -along with GNU Classpath; see the file COPYING. If not, write to the -Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA -02110-1301 USA. - -Linking this library statically or dynamically with other modules is -making a combined work based on this library. Thus, the terms and -conditions of the GNU General Public License cover the whole -combination. - -As a special exception, the copyright holders of this library give you -permission to link this library with independent modules to produce an -executable, regardless of the license terms of these independent -modules, and to copy and distribute the resulting executable under -terms of your choice, provided that you also meet, for each linked -independent module, the terms and conditions of the license of that -module. An independent module is a module which is not derived from -or based on this library. If you modify this library, you may extend -this exception to your version of the library, but you are not -obligated to do so. If you do not wish to do so, delete this -exception statement from your version. */ - - -package java.lang; - -import gnu.classpath.SystemProperties; -import gnu.classpath.VMStackWalker; -import gnu.java.util.DoubleEnumeration; -import gnu.java.util.EmptyEnumeration; - -import java.io.IOException; -import java.io.InputStream; -import java.lang.ref.WeakReference; -import java.net.URL; -import java.nio.ByteBuffer; -import java.security.CodeSource; -import java.security.PermissionCollection; -import java.security.Policy; -import java.security.ProtectionDomain; -import java.util.Enumeration; -import java.util.HashMap; -import java.util.Map; - -import java.util.concurrent.ConcurrentHashMap; -import java.lang.annotation.Annotation; - -/** - * The ClassLoader is a way of customizing the way Java gets its classes - * and loads them into memory. The verifier and other standard Java things - * still run, but the ClassLoader is allowed great flexibility in determining - * where to get the classfiles and when to load and resolve them. For that - * matter, a custom ClassLoader can perform on-the-fly code generation or - * modification! - * - * <p>Every classloader has a parent classloader that is consulted before - * the 'child' classloader when classes or resources should be loaded. - * This is done to make sure that classes can be loaded from an hierarchy of - * multiple classloaders and classloaders do not accidentially redefine - * already loaded classes by classloaders higher in the hierarchy. - * - * <p>The grandparent of all classloaders is the bootstrap classloader, which - * loads all the standard system classes as implemented by GNU Classpath. The - * other special classloader is the system classloader (also called - * application classloader) that loads all classes from the CLASSPATH - * (<code>java.class.path</code> system property). The system classloader - * is responsible for finding the application classes from the classpath, - * and delegates all requests for the standard library classes to its parent - * the bootstrap classloader. Most programs will load all their classes - * through the system classloaders. - * - * <p>The bootstrap classloader in GNU Classpath is implemented as a couple of - * static (native) methods on the package private class - * <code>java.lang.VMClassLoader</code>, the system classloader is an - * instance of <code>gnu.java.lang.SystemClassLoader</code> - * (which is a subclass of <code>java.net.URLClassLoader</code>). - * - * <p>Users of a <code>ClassLoader</code> will normally just use the methods - * <ul> - * <li> <code>loadClass()</code> to load a class.</li> - * <li> <code>getResource()</code> or <code>getResourceAsStream()</code> - * to access a resource.</li> - * <li> <code>getResources()</code> to get an Enumeration of URLs to all - * the resources provided by the classloader and its parents with the - * same name.</li> - * </ul> - * - * <p>Subclasses should implement the methods - * <ul> - * <li> <code>findClass()</code> which is called by <code>loadClass()</code> - * when the parent classloader cannot provide a named class.</li> - * <li> <code>findResource()</code> which is called by - * <code>getResource()</code> when the parent classloader cannot provide - * a named resource.</li> - * <li> <code>findResources()</code> which is called by - * <code>getResource()</code> to combine all the resources with the - * same name from the classloader and its parents.</li> - * <li> <code>findLibrary()</code> which is called by - * <code>Runtime.loadLibrary()</code> when a class defined by the - * classloader wants to load a native library.</li> - * </ul> - * - * @author John Keiser - * @author Mark Wielaard - * @author Eric Blake (ebb9@email.byu.edu) - * @see Class - * @since 1.0 - */ -public abstract class ClassLoader -{ - /** - * All classes loaded by this classloader. VM's may choose to implement - * this cache natively; but it is here available for use if necessary. It - * is not private in order to allow native code (and trusted subclasses) - * access to this field. - */ - final HashMap loadedClasses = new HashMap(); - - /** - * Loading constraints registered with this classloader. This maps - * a class name to a weak reference to a class. When the reference - * is non-null, it means that a reference to the name must resolve - * to the indicated class. - */ - final HashMap<String, WeakReference<Class>> loadingConstraints - = new HashMap<String, WeakReference<Class>>(); - - /** - * All packages defined by this classloader. It is not private in order to - * allow native code (and trusted subclasses) access to this field. - */ - final HashMap definedPackages = new HashMap(); - - /** - * The classloader that is consulted before this classloader. - * If null then the parent is the bootstrap classloader. - */ - private final ClassLoader parent; - - /** - * This is true if this classloader was successfully initialized. - * This flag is needed to avoid a class loader attack: even if the - * security manager rejects an attempt to create a class loader, the - * malicious class could have a finalize method which proceeds to - * define classes. - */ - private final boolean initialized; - - /** - * System/Application classloader: defaults to an instance of - * gnu.java.lang.SystemClassLoader, unless the first invocation of - * getSystemClassLoader loads another class loader because of the - * java.system.class.loader property. The initialization of this field - * is somewhat circular - getSystemClassLoader() checks whether this - * field is null in order to bypass a security check. - */ - static final ClassLoader systemClassLoader = - VMClassLoader.getSystemClassLoader(); - - /** - * This cache maps from a Class to its associated annotations. It's - * declared here so that when this class loader becomes unreachable, - * so will the corresponding cache. - */ - - private final ConcurrentHashMap<AnnotationsKey,Object[]> - declaredAnnotations - = new ConcurrentHashMap<AnnotationsKey,Object[]>(); - - static final class AnnotationsKey - { - final int /* jv_attr_type */ member_type; - final int member_index; - final int /* jv_attr_kind */ kind_req; - final Class declaringClass; - final int hashCode; - - public AnnotationsKey (Class declaringClass, - int member_type, - int member_index, - int kind_req) - { - this.member_type = member_type; - this.member_index = member_index; - this.kind_req = kind_req; - this.declaringClass = declaringClass; - hashCode = (member_type ^ member_index ^ kind_req - ^ declaringClass.hashCode()); - } - - public boolean equals(Object obj) - { - AnnotationsKey other = (AnnotationsKey)obj; - return (this.member_type == other.member_type - && this.member_index == other.member_index - && this.kind_req == other.kind_req - && this.declaringClass == other.declaringClass); - } - - public int hashCode() - { - return hashCode; - } - - public static final Annotation[] NIL = new Annotation[0]; - } - - final Object[] getDeclaredAnnotations(Class declaringClass, - int member_type, - int member_index, - int kind_req) - { - Object[] result - = declaredAnnotations.get (new AnnotationsKey - (declaringClass, - member_type, - member_index, - kind_req)); - if (result != AnnotationsKey.NIL && result != null) - return (Object[])result.clone(); - return null; - } - - final Object[] putDeclaredAnnotations(Class declaringClass, - int member_type, - int member_index, - int kind_req, - Object[] annotations) - { - declaredAnnotations.put - (new AnnotationsKey - (declaringClass, member_type, - member_index, kind_req), - annotations == null ? AnnotationsKey.NIL : annotations); - - return annotations == null ? null : (Object[])annotations.clone(); - } - - static - { - // Find out if we have to install a default security manager. Note - // that this is done here because we potentially need the system - // class loader to load the security manager and note also that we - // don't need the security manager until the system class loader - // is created. If the runtime chooses to use a class loader that - // doesn't have the system class loader as its parent, it is - // responsible for setting up a security manager before doing so. - String secman = SystemProperties.getProperty("java.security.manager"); - if (secman != null && SecurityManager.current == null) - { - if (secman.equals("") || secman.equals("default")) - { - SecurityManager.current = new SecurityManager(); - } - else - { - try - { - Class cl = Class.forName(secman, false, systemClassLoader); - SecurityManager.current = (SecurityManager) cl.newInstance(); - } - catch (Exception x) - { - throw (InternalError) - new InternalError("Unable to create SecurityManager") - .initCause(x); - } - } - } - } - - /** - * The default protection domain, used when defining a class with a null - * paramter for the domain. - */ - static final ProtectionDomain defaultProtectionDomain; - static - { - CodeSource cs = new CodeSource(null, null); - PermissionCollection perm = Policy.getPolicy().getPermissions(cs); - defaultProtectionDomain = new ProtectionDomain(cs, perm); - } - - /** - * The desired assertion status of classes loaded by this loader, if not - * overridden by package or class instructions. - */ - // Package visible for use by Class. - boolean defaultAssertionStatus = VMClassLoader.defaultAssertionStatus(); - - /** - * The command-line state of the package assertion status overrides. This - * map is never modified, so it does not need to be synchronized. - */ - // Package visible for use by Class. - static final Map systemPackageAssertionStatus - = VMClassLoader.packageAssertionStatus(); - - /** - * The map of package assertion status overrides, or null if no package - * overrides have been specified yet. The values of the map should be - * Boolean.TRUE or Boolean.FALSE, and the unnamed package is represented - * by the null key. This map must be synchronized on this instance. - */ - // Package visible for use by Class. - Map packageAssertionStatus; - - /** - * The command-line state of the class assertion status overrides. This - * map is never modified, so it does not need to be synchronized. - */ - // Package visible for use by Class. - static final Map systemClassAssertionStatus - = VMClassLoader.classAssertionStatus(); - - /** - * The map of class assertion status overrides, or null if no class - * overrides have been specified yet. The values of the map should be - * Boolean.TRUE or Boolean.FALSE. This map must be synchronized on this - * instance. - */ - // Package visible for use by Class. - Map classAssertionStatus; - - /** - * Create a new ClassLoader with as parent the system classloader. There - * may be a security check for <code>checkCreateClassLoader</code>. - * - * @throws SecurityException if the security check fails - */ - protected ClassLoader() throws SecurityException - { - this(systemClassLoader); - } - - /** - * Create a new ClassLoader with the specified parent. The parent will - * be consulted when a class or resource is requested through - * <code>loadClass()</code> or <code>getResource()</code>. Only when the - * parent classloader cannot provide the requested class or resource the - * <code>findClass()</code> or <code>findResource()</code> method - * of this classloader will be called. There may be a security check for - * <code>checkCreateClassLoader</code>. - * - * @param parent the classloader's parent, or null for the bootstrap - * classloader - * @throws SecurityException if the security check fails - * @since 1.2 - */ - protected ClassLoader(ClassLoader parent) - { - // May we create a new classloader? - SecurityManager sm = System.getSecurityManager(); - if (sm != null) - sm.checkCreateClassLoader(); - this.parent = parent; - this.initialized = true; - } - - /** - * Load a class using this ClassLoader or its parent, without resolving - * it. Calls <code>loadClass(name, false)</code>. - * - * <p>Subclasses should not override this method but should override - * <code>findClass()</code> which is called by this method.</p> - * - * @param name the name of the class relative to this ClassLoader - * @return the loaded class - * @throws ClassNotFoundException if the class cannot be found - */ - public Class<?> loadClass(String name) throws ClassNotFoundException - { - return loadClass(name, false); - } - - private native Class loadClassFromSig(String name) - throws ClassNotFoundException; - - /** - * Load a class using this ClassLoader or its parent, possibly resolving - * it as well using <code>resolveClass()</code>. It first tries to find - * out if the class has already been loaded through this classloader by - * calling <code>findLoadedClass()</code>. Then it calls - * <code>loadClass()</code> on the parent classloader (or when there is - * no parent it uses the VM bootclassloader). If the class is still - * not loaded it tries to create a new class by calling - * <code>findClass()</code>. Finally when <code>resolve</code> is - * <code>true</code> it also calls <code>resolveClass()</code> on the - * newly loaded class. - * - * <p>Subclasses should not override this method but should override - * <code>findClass()</code> which is called by this method.</p> - * - * @param name the fully qualified name of the class to load - * @param resolve whether or not to resolve the class - * @return the loaded class - * @throws ClassNotFoundException if the class cannot be found - */ - protected synchronized Class<?> loadClass(String name, boolean resolve) - throws ClassNotFoundException - { - SecurityManager sm = SecurityManager.current; - if (sm != null) - { - int lastDot = name.lastIndexOf('.'); - if (lastDot != -1) - sm.checkPackageAccess(name.substring(0, lastDot)); - } - - // Arrays are handled specially. - Class c; - if (name.length() > 0 && name.charAt(0) == '[') - c = loadClassFromSig(name); - else - { - // Have we already loaded this class? - c = findLoadedClass(name); - if (c == null) - { - // Can the class be loaded by a parent? - try - { - if (parent == null) - { - c = VMClassLoader.loadClass(name, resolve); - if (c != null) - return c; - } - else - { - return parent.loadClass(name, resolve); - } - } - catch (ClassNotFoundException e) - { - } - // Still not found, we have to do it ourself. - c = findClass(name); - } - } - if (resolve) - resolveClass(c); - return c; - } - - /** - * Called for every class name that is needed but has not yet been - * defined by this classloader or one of its parents. It is called by - * <code>loadClass()</code> after both <code>findLoadedClass()</code> and - * <code>parent.loadClass()</code> couldn't provide the requested class. - * - * <p>The default implementation throws a - * <code>ClassNotFoundException</code>. Subclasses should override this - * method. An implementation of this method in a subclass should get the - * class bytes of the class (if it can find them), if the package of the - * requested class doesn't exist it should define the package and finally - * it should call define the actual class. It does not have to resolve the - * class. It should look something like the following:<br> - * - * <pre> - * // Get the bytes that describe the requested class - * byte[] classBytes = classLoaderSpecificWayToFindClassBytes(name); - * // Get the package name - * int lastDot = name.lastIndexOf('.'); - * if (lastDot != -1) - * { - * String packageName = name.substring(0, lastDot); - * // Look if the package already exists - * if (getPackage(packageName) == null) - * { - * // define the package - * definePackage(packageName, ...); - * } - * } - * // Define and return the class - * return defineClass(name, classBytes, 0, classBytes.length); - * </pre> - * - * <p><code>loadClass()</code> makes sure that the <code>Class</code> - * returned by <code>findClass()</code> will later be returned by - * <code>findLoadedClass()</code> when the same class name is requested. - * - * @param name class name to find (including the package name) - * @return the requested Class - * @throws ClassNotFoundException when the class can not be found - * @since 1.2 - */ - protected Class<?> findClass(String name) throws ClassNotFoundException - { - throw new ClassNotFoundException(name); - } - - /** - * Helper to define a class using a string of bytes. This version is not - * secure. - * - * @param data the data representing the classfile, in classfile format - * @param offset the offset into the data where the classfile starts - * @param len the length of the classfile data in the array - * @return the class that was defined - * @throws ClassFormatError if data is not in proper classfile format - * @throws IndexOutOfBoundsException if offset or len is negative, or - * offset + len exceeds data - * @deprecated use {@link #defineClass(String, byte[], int, int)} instead - */ - protected final Class<?> defineClass(byte[] data, int offset, int len) - throws ClassFormatError - { - return defineClass(null, data, offset, len); - } - - /** - * Helper to define a class using a string of bytes without a - * ProtectionDomain. Subclasses should call this method from their - * <code>findClass()</code> implementation. The name should use '.' - * separators, and discard the trailing ".class". The default protection - * domain has the permissions of - * <code>Policy.getPolicy().getPermissions(new CodeSource(null, null))</code>. - * - * @param name the name to give the class, or null if unknown - * @param data the data representing the classfile, in classfile format - * @param offset the offset into the data where the classfile starts - * @param len the length of the classfile data in the array - * @return the class that was defined - * @throws ClassFormatError if data is not in proper classfile format - * @throws IndexOutOfBoundsException if offset or len is negative, or - * offset + len exceeds data - * @throws SecurityException if name starts with "java." - * @since 1.1 - */ - protected final Class<?> defineClass(String name, byte[] data, int offset, - int len) throws ClassFormatError - { - return defineClass(name, data, offset, len, null); - } - - /** - * Helper to define a class using a string of bytes. Subclasses should call - * this method from their <code>findClass()</code> implementation. If the - * domain is null, the default of - * <code>Policy.getPolicy().getPermissions(new CodeSource(null, null))</code> - * is used. Once a class has been defined in a package, all further classes - * in that package must have the same set of certificates or a - * SecurityException is thrown. - * - * @param name the name to give the class. null if unknown - * @param data the data representing the classfile, in classfile format - * @param offset the offset into the data where the classfile starts - * @param len the length of the classfile data in the array - * @param domain the ProtectionDomain to give to the class, null for the - * default protection domain - * @return the class that was defined - * @throws ClassFormatError if data is not in proper classfile format - * @throws IndexOutOfBoundsException if offset or len is negative, or - * offset + len exceeds data - * @throws SecurityException if name starts with "java.", or if certificates - * do not match up - * @since 1.2 - */ - protected final synchronized Class<?> defineClass(String name, byte[] data, - int offset, int len, - ProtectionDomain domain) - throws ClassFormatError - { - checkInitialized(); - if (domain == null) - domain = defaultProtectionDomain; - - Class retval = VMClassLoader.defineClass(this, name, data, - offset, len, domain); - loadedClasses.put(retval.getName(), retval); - return retval; - } - - /** - * Helper to define a class using the contents of a byte buffer. If - * the domain is null, the default of - * <code>Policy.getPolicy().getPermissions(new CodeSource(null, - * null))</code> is used. Once a class has been defined in a - * package, all further classes in that package must have the same - * set of certificates or a SecurityException is thrown. - * - * @param name the name to give the class. null if unknown - * @param buf a byte buffer containing bytes that form a class. - * @param domain the ProtectionDomain to give to the class, null for the - * default protection domain - * @return the class that was defined - * @throws ClassFormatError if data is not in proper classfile format - * @throws NoClassDefFoundError if the supplied name is not the same as - * the one specified by the byte buffer. - * @throws SecurityException if name starts with "java.", or if certificates - * do not match up - * @since 1.5 - */ - protected final Class<?> defineClass(String name, ByteBuffer buf, - ProtectionDomain domain) - throws ClassFormatError - { - byte[] data = new byte[buf.remaining()]; - buf.get(data); - return defineClass(name, data, 0, data.length, domain); - } - - /** - * Links the class, if that has not already been done. Linking basically - * resolves all references to other classes made by this class. - * - * @param c the class to resolve - * @throws NullPointerException if c is null - * @throws LinkageError if linking fails - */ - protected final void resolveClass(Class<?> c) - { - checkInitialized(); - VMClassLoader.resolveClass(c); - } - - /** - * Helper to find a Class using the system classloader, possibly loading it. - * A subclass usually does not need to call this, if it correctly - * overrides <code>findClass(String)</code>. - * - * @param name the name of the class to find - * @return the found class - * @throws ClassNotFoundException if the class cannot be found - */ - protected final Class<?> findSystemClass(String name) - throws ClassNotFoundException - { - checkInitialized(); - return Class.forName(name, false, systemClassLoader); - } - - /** - * Returns the parent of this classloader. If the parent of this - * classloader is the bootstrap classloader then this method returns - * <code>null</code>. A security check may be performed on - * <code>RuntimePermission("getClassLoader")</code>. - * - * @return the parent <code>ClassLoader</code> - * @throws SecurityException if the security check fails - * @since 1.2 - */ - public final ClassLoader getParent() - { - // Check if we may return the parent classloader. - SecurityManager sm = System.getSecurityManager(); - if (sm != null) - { - ClassLoader cl = VMStackWalker.getCallingClassLoader(); - if (cl != null && ! cl.isAncestorOf(this)) - sm.checkPermission(new RuntimePermission("getClassLoader")); - } - return parent; - } - - /** - * Helper to set the signers of a class. This should be called after - * defining the class. - * - * @param c the Class to set signers of - * @param signers the signers to set - * @since 1.1 - */ - protected final void setSigners(Class<?> c, Object[] signers) - { - checkInitialized(); - c.setSigners(signers); - } - - /** - * Helper to find an already-loaded class in this ClassLoader. - * - * @param name the name of the class to find - * @return the found Class, or null if it is not found - * @since 1.1 - */ - protected final synchronized Class<?> findLoadedClass(String name) - { - checkInitialized(); - // NOTE: If the VM is keeping its own cache, it may make sense to have - // this method be native. - return (Class) loadedClasses.get(name); - } - - /** - * Get the URL to a resource using this classloader or one of its parents. - * First tries to get the resource by calling <code>getResource()</code> - * on the parent classloader. If the parent classloader returns null then - * it tries finding the resource by calling <code>findResource()</code> on - * this classloader. The resource name should be separated by '/' for path - * elements. - * - * <p>Subclasses should not override this method but should override - * <code>findResource()</code> which is called by this method. - * - * @param name the name of the resource relative to this classloader - * @return the URL to the resource or null when not found - */ - public URL getResource(String name) - { - URL result; - - if (parent == null) - result = VMClassLoader.getResource(name); - else - result = parent.getResource(name); - - if (result == null) - result = findResource(name); - return result; - } - - /** - * Returns an Enumeration of all resources with a given name that can - * be found by this classloader and its parents. Certain classloaders - * (such as the URLClassLoader when given multiple jar files) can have - * multiple resources with the same name that come from multiple locations. - * It can also occur that a parent classloader offers a resource with a - * certain name and the child classloader also offers a resource with that - * same name. <code>getResource()</code> only offers the first resource (of the - * parent) with a given name. This method lists all resources with the - * same name. The name should use '/' as path separators. - * - * <p>The Enumeration is created by first calling <code>getResources()</code> - * on the parent classloader and then calling <code>findResources()</code> - * on this classloader.</p> - * - * @param name the resource name - * @return an enumaration of all resources found - * @throws IOException if I/O errors occur in the process - * @since 1.2 - * @specnote this was <code>final</code> prior to 1.5 - */ - public Enumeration<URL> getResources(String name) throws IOException - { - Enumeration<URL> parentResources; - if (parent == null) - parentResources = VMClassLoader.getResources(name); - else - parentResources = parent.getResources(name); - return new DoubleEnumeration<URL>(parentResources, findResources(name)); - } - - /** - * Called whenever all locations of a named resource are needed. - * It is called by <code>getResources()</code> after it has called - * <code>parent.getResources()</code>. The results are combined by - * the <code>getResources()</code> method. - * - * <p>The default implementation always returns an empty Enumeration. - * Subclasses should override it when they can provide an Enumeration of - * URLs (possibly just one element) to the named resource. - * The first URL of the Enumeration should be the same as the one - * returned by <code>findResource</code>. - * - * @param name the name of the resource to be found - * @return a possibly empty Enumeration of URLs to the named resource - * @throws IOException if I/O errors occur in the process - * @since 1.2 - */ - protected Enumeration<URL> findResources(String name) throws IOException - { - return new EmptyEnumeration<URL>(); - } - - /** - * Called whenever a resource is needed that could not be provided by - * one of the parents of this classloader. It is called by - * <code>getResource()</code> after <code>parent.getResource()</code> - * couldn't provide the requested resource. - * - * <p>The default implementation always returns null. Subclasses should - * override this method when they can provide a way to return a URL - * to a named resource. - * - * @param name the name of the resource to be found - * @return a URL to the named resource or null when not found - * @since 1.2 - */ - protected URL findResource(String name) - { - return null; - } - - /** - * Get the URL to a resource using the system classloader. - * - * @param name the name of the resource relative to the system classloader - * @return the URL to the resource - * @since 1.1 - */ - public static final URL getSystemResource(String name) - { - return systemClassLoader.getResource(name); - } - - /** - * Get an Enumeration of URLs to resources with a given name using the - * the system classloader. The enumeration firsts lists the resources with - * the given name that can be found by the bootstrap classloader followed - * by the resources with the given name that can be found on the classpath. - * - * @param name the name of the resource relative to the system classloader - * @return an Enumeration of URLs to the resources - * @throws IOException if I/O errors occur in the process - * @since 1.2 - */ - public static Enumeration<URL> getSystemResources(String name) - throws IOException - { - return systemClassLoader.getResources(name); - } - - /** - * Get a resource as stream using this classloader or one of its parents. - * First calls <code>getResource()</code> and if that returns a URL to - * the resource then it calls and returns the InputStream given by - * <code>URL.openStream()</code>. - * - * <p>Subclasses should not override this method but should override - * <code>findResource()</code> which is called by this method. - * - * @param name the name of the resource relative to this classloader - * @return an InputStream to the resource, or null - * @since 1.1 - */ - public InputStream getResourceAsStream(String name) - { - try - { - URL url = getResource(name); - if (url == null) - return null; - return url.openStream(); - } - catch (IOException e) - { - return null; - } - } - - /** - * Get a resource using the system classloader. - * - * @param name the name of the resource relative to the system classloader - * @return an input stream for the resource, or null - * @since 1.1 - */ - public static final InputStream getSystemResourceAsStream(String name) - { - try - { - URL url = getSystemResource(name); - if (url == null) - return null; - return url.openStream(); - } - catch (IOException e) - { - return null; - } - } - - /** - * Returns the system classloader. The system classloader (also called - * the application classloader) is the classloader that is used to - * load the application classes on the classpath (given by the system - * property <code>java.class.path</code>. This is set as the context - * class loader for a thread. The system property - * <code>java.system.class.loader</code>, if defined, is taken to be the - * name of the class to use as the system class loader, which must have - * a public constructor which takes a ClassLoader as a parent. The parent - * class loader passed in the constructor is the default system class - * loader. - * - * <p>Note that this is different from the bootstrap classloader that - * actually loads all the real "system" classes (the bootstrap classloader - * is the parent of the returned system classloader). - * - * <p>A security check will be performed for - * <code>RuntimePermission("getClassLoader")</code> if the calling class - * is not a parent of the system class loader. - * - * @return the system class loader - * @throws SecurityException if the security check fails - * @throws IllegalStateException if this is called recursively - * @throws Error if <code>java.system.class.loader</code> fails to load - * @since 1.2 - */ - public static ClassLoader getSystemClassLoader() - { - // Check if we may return the system classloader - SecurityManager sm = System.getSecurityManager(); - if (sm != null) - { - ClassLoader cl = VMStackWalker.getCallingClassLoader(); - if (cl != null && cl != systemClassLoader) - sm.checkPermission(new RuntimePermission("getClassLoader")); - } - - return systemClassLoader; - } - - /** - * Defines a new package and creates a Package object. The package should - * be defined before any class in the package is defined with - * <code>defineClass()</code>. The package should not yet be defined - * before in this classloader or in one of its parents (which means that - * <code>getPackage()</code> should return <code>null</code>). All - * parameters except the <code>name</code> of the package may be - * <code>null</code>. - * - * <p>Subclasses should call this method from their <code>findClass()</code> - * implementation before calling <code>defineClass()</code> on a Class - * in a not yet defined Package (which can be checked by calling - * <code>getPackage()</code>). - * - * @param name the name of the Package - * @param specTitle the name of the specification - * @param specVendor the name of the specification designer - * @param specVersion the version of this specification - * @param implTitle the name of the implementation - * @param implVendor the vendor that wrote this implementation - * @param implVersion the version of this implementation - * @param sealed if sealed the origin of the package classes - * @return the Package object for the specified package - * @throws IllegalArgumentException if the package name is null or it - * was already defined by this classloader or one of its parents - * @see Package - * @since 1.2 - */ - protected Package definePackage(String name, String specTitle, - String specVendor, String specVersion, - String implTitle, String implVendor, - String implVersion, URL sealed) - { - if (getPackage(name) != null) - throw new IllegalArgumentException("Package " + name - + " already defined"); - Package p = new Package(name, specTitle, specVendor, specVersion, - implTitle, implVendor, implVersion, sealed, this); - synchronized (definedPackages) - { - definedPackages.put(name, p); - } - return p; - } - - /** - * Returns the Package object for the requested package name. It returns - * null when the package is not defined by this classloader or one of its - * parents. - * - * @param name the package name to find - * @return the package, if defined - * @since 1.2 - */ - protected Package getPackage(String name) - { - Package p; - if (parent == null) - p = VMClassLoader.getPackage(name); - else - p = parent.getPackage(name); - - if (p == null) - { - synchronized (definedPackages) - { - p = (Package) definedPackages.get(name); - } - } - return p; - } - - /** - * Returns all Package objects defined by this classloader and its parents. - * - * @return an array of all defined packages - * @since 1.2 - */ - protected Package[] getPackages() - { - // Get all our packages. - Package[] packages; - synchronized(definedPackages) - { - packages = new Package[definedPackages.size()]; - definedPackages.values().toArray(packages); - } - - // If we have a parent get all packages defined by our parents. - Package[] parentPackages; - if (parent == null) - parentPackages = VMClassLoader.getPackages(); - else - parentPackages = parent.getPackages(); - - Package[] allPackages = new Package[parentPackages.length - + packages.length]; - System.arraycopy(parentPackages, 0, allPackages, 0, - parentPackages.length); - System.arraycopy(packages, 0, allPackages, parentPackages.length, - packages.length); - return allPackages; - } - - /** - * Called by <code>Runtime.loadLibrary()</code> to get an absolute path - * to a (system specific) library that was requested by a class loaded - * by this classloader. The default implementation returns - * <code>null</code>. It should be implemented by subclasses when they - * have a way to find the absolute path to a library. If this method - * returns null the library is searched for in the default locations - * (the directories listed in the <code>java.library.path</code> system - * property). - * - * @param name the (system specific) name of the requested library - * @return the full pathname to the requested library, or null - * @see Runtime#loadLibrary(String) - * @since 1.2 - */ - protected String findLibrary(String name) - { - return null; - } - - /** - * Set the default assertion status for classes loaded by this classloader, - * used unless overridden by a package or class request. - * - * @param enabled true to set the default to enabled - * @see #setClassAssertionStatus(String, boolean) - * @see #setPackageAssertionStatus(String, boolean) - * @see #clearAssertionStatus() - * @since 1.4 - */ - public void setDefaultAssertionStatus(boolean enabled) - { - defaultAssertionStatus = enabled; - } - - /** - * Set the default assertion status for packages, used unless overridden - * by a class request. This default also covers subpackages, unless they - * are also specified. The unnamed package should use null for the name. - * - * @param name the package (and subpackages) to affect - * @param enabled true to set the default to enabled - * @see #setDefaultAssertionStatus(boolean) - * @see #setClassAssertionStatus(String, boolean) - * @see #clearAssertionStatus() - * @since 1.4 - */ - public synchronized void setPackageAssertionStatus(String name, - boolean enabled) - { - if (packageAssertionStatus == null) - packageAssertionStatus - = new HashMap(systemPackageAssertionStatus); - packageAssertionStatus.put(name, Boolean.valueOf(enabled)); - } - - /** - * Set the default assertion status for a class. This only affects the - * status of top-level classes, any other string is harmless. - * - * @param name the class to affect - * @param enabled true to set the default to enabled - * @throws NullPointerException if name is null - * @see #setDefaultAssertionStatus(boolean) - * @see #setPackageAssertionStatus(String, boolean) - * @see #clearAssertionStatus() - * @since 1.4 - */ - public synchronized void setClassAssertionStatus(String name, - boolean enabled) - { - if (classAssertionStatus == null) - classAssertionStatus = new HashMap(systemClassAssertionStatus); - // The toString() hack catches null, as required. - classAssertionStatus.put(name.toString(), Boolean.valueOf(enabled)); - } - - /** - * Resets the default assertion status of this classloader, its packages - * and classes, all to false. This allows overriding defaults inherited - * from the command line. - * - * @see #setDefaultAssertionStatus(boolean) - * @see #setClassAssertionStatus(String, boolean) - * @see #setPackageAssertionStatus(String, boolean) - * @since 1.4 - */ - public synchronized void clearAssertionStatus() - { - defaultAssertionStatus = false; - packageAssertionStatus = new HashMap(); - classAssertionStatus = new HashMap(); - } - - /** - * Return true if this loader is either the specified class loader - * or an ancestor thereof. - * @param loader the class loader to check - */ - final boolean isAncestorOf(ClassLoader loader) - { - while (loader != null) - { - if (this == loader) - return true; - loader = loader.parent; - } - return false; - } - - /** - * Before doing anything "dangerous" please call this method to make sure - * this class loader instance was properly constructed (and not obtained - * by exploiting the finalizer attack) - * @see #initialized - */ - private void checkInitialized() - { - if (! initialized) - throw new SecurityException("attempt to use uninitialized class loader"); - } -} |