bundles/org.eclipse.osgi/defaultAdaptor/src/org/eclipse/osgi/framework/adaptor/core/AbstractClassLoader.java - equinox/rt.equinox.framework - Git at Google

 /*******************************************************************************
  * Copyright (c) 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Common Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.osgi.framework.adaptor.core;

 import java.io.IOException;
 import java.net.URL;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
 import java.security.ProtectionDomain;
 import java.util.Enumeration;

 import org.eclipse.osgi.framework.adaptor.BundleClassLoader;
 import org.eclipse.osgi.framework.adaptor.ClassLoaderDelegate;
 import org.eclipse.osgi.framework.adaptor.ImportResourceNotFoundException;
 import org.eclipse.osgi.framework.debug.Debug;

 /**
  * The AbstractClassLoader provides some basic functionality that all
  * BundleClassLoaders must provide.  It properly delegates resource and
  * class lookups to a parent classloader and the to a ClassLoaderDelegate.
  */
 public abstract class AbstractClassLoader extends ClassLoader implements BundleClassLoader {

 	/**
 	 * The delegate used to get classes and resources from.  The delegate
 	 * must always be queried first before the local ClassLoader is searched for
 	 * a class or resource.
 	 */
 	protected ClassLoaderDelegate delegate;

 	/**
 	 * The host ProtectionDomain to use to define classes.
 	 */
 	protected ProtectionDomain hostdomain;

 	/**
 	 * The host classpath entries for this classloader
 	 */
 	protected String[] hostclasspath;

 	/**
 	 * Indicates this class loader is closed.
 	 */
 	protected boolean closed = false;

 	/**
 	 * BundleClassLoader constructor.
 	 * @param delegate The ClassLoaderDelegate for this bundle.
 	 * @param domain The ProtectionDomain for this bundle.
 	 * @param parent The parent classloader to use.  Must not be null.
 	 * @param classpath The classpath entries to use for the host.
 	 */
 	public AbstractClassLoader(ClassLoaderDelegate delegate, ProtectionDomain domain, String[] classpath, ClassLoader parent) {
 		super(parent);
 		this.delegate = delegate;
 		this.hostdomain = domain;
 		this.hostclasspath = classpath;
 	}

 	/**
 	 * Loads a class for the bundle.  First delegate.findClass(name) is called.
 	 * The delegate will query the system class loader, bundle imports, bundle
 	 * local classes, bundle hosts and fragments.  The delegate will call
 	 * BundleClassLoader.findLocalClass(name) to find a class local to this
 	 * bundle.
 	 * @param name the name of the class to load.
 	 * @param resolve indicates whether to resolve the loaded class or not.
 	 * @return The Class object.
 	 * @throws ClassNotFoundException if the class is not found.
 	 */
 	protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
 		if (closed)
 			throw new ClassNotFoundException(name);

 		if (Debug.DEBUG && Debug.DEBUG_LOADER)
 			Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ")");

 		try {
 			// First check the parent classloader for system classes.
 			ClassLoader parent = getParentPrivileged();
 			if (parent != null)
 				try {
 					return parent.loadClass(name);
 				} catch (ClassNotFoundException e) {
 					// Do nothing. continue to delegate.
 				}

 			// Just ask the delegate.  This could result in findLocalClass(name) being called.
 			Class clazz = delegate.findClass(name);
 			// resolve the class if asked to.
 			if (resolve)
 				resolveClass(clazz);
 			return (clazz);
 		} catch (Error e) {
 			if (Debug.DEBUG && Debug.DEBUG_LOADER) {
 				Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ") failed.");
 				Debug.printStackTrace(e);
 			}
 			throw e;
 		} catch (ClassNotFoundException e) {
 			// If the class is not found do not try to look for it locally.
 			// The delegate would have already done that for us.
 			if (Debug.DEBUG && Debug.DEBUG_LOADER) {
 				Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ") failed.");
 				Debug.printStackTrace(e);
 			}
 			throw e;
 		}
 	}

 	/**
 	 * Finds a class local to this bundle.  The bundle class path is used
 	 * to search for the class.  The delegate must not be used.  This method
 	 * is abstract to force extending classes to implement this method instead
 	 * of using the ClassLoader.findClass(String) method.
 	 * @param name The classname of the class to find
 	 * @return The Class object.
 	 * @throws ClassNotFoundException if the class is not found.
 	 */
 	abstract protected Class findClass(String name) throws ClassNotFoundException;

 	/**
 	 * Gets a resource for the bundle.  First delegate.findResource(name) is
 	 * called. The delegate will query the system class loader, bundle imports,
 	 * bundle local resources, bundle hosts and fragments.  The delegate will
 	 * call BundleClassLoader.findLocalResource(name) to find a resource local
 	 * to this bundle.
 	 * @param name The resource path to get.
 	 * @return The URL of the resource or null if it does not exist.
 	 */
 	public URL getResource(String name) {
 		if (closed) {
 			return null;
 		}
 		if (Debug.DEBUG && Debug.DEBUG_LOADER) {
 			Debug.println("BundleClassLoader[" + delegate + "].getResource(" + name + ")");
 		}

 		try {
 			URL url = null;
 			// First check the parent classloader for system resources.
 			ClassLoader parent = getParentPrivileged();
 			if (parent != null)
 				url = parent.getResource(name);
 			if (url != null) {
 				return (url);
 			}
 			url = delegate.findResource(name);
 			if (url != null) {
 				return (url);
 			}
 		} catch (ImportResourceNotFoundException e) {
 		}

 		if (Debug.DEBUG && Debug.DEBUG_LOADER) {
 			Debug.println("BundleClassLoader[" + delegate + "].getResource(" + name + ") failed.");
 		}

 		return (null);
 	}

 	/**
 	 * Finds a resource local to this bundle.  Simply calls
 	 * findResourceImpl(name) to find the resource.
 	 * @param name The resource path to find.
 	 * @return The URL of the resource or null if it does not exist.
 	 */
 	abstract protected URL findResource(String name);

 	/**
 	 * Finds all resources with the specified name.  This method must call
 	 * delegate.findResources(name) to find all the resources.
 	 * @param name The resource path to find.
 	 * @return An Enumeration of all resources found or null if the resource.
 	 */
 	protected Enumeration findResources(String name) throws IOException {
 		try {
 			return (delegate.findResources(name));
 		} catch (Exception e) {
 			if (Debug.DEBUG && Debug.DEBUG_LOADER) {
 				Debug.println("BundleClassLoader[" + delegate + "].findResources(" + name + ") failed.");
 				Debug.printStackTrace(e);
 			}
 			return null;
 		}
 	}

 	/**
 	 * Finds a library for this bundle.  Simply calls
 	 * delegate.findLibrary(libname) to find the library.
 	 * @param libname The library to find.
 	 * @return The URL of the resource or null if it does not exist.
 	 */
 	protected String findLibrary(String libname) {
 		return delegate.findLibrary(libname);
 	}

 	/**
 	 * Finds a local resource in the BundleClassLoader without
 	 * consulting the delegate.
 	 * @param resource the resource path to find.
 	 * @return a URL to the resource or null if the resource does not exist.
 	 */
 	public URL findLocalResource(String resource) {
 		return findResource(resource);
 	}

 	/**
 	 * Finds a local class in the BundleClassLoader without
 	 * consulting the delegate.
 	 * @param classname the classname to find.
 	 * @return The class object found.
 	 * @throws ClassNotFoundException if the classname does not exist locally.
 	 */
 	public Class findLocalClass(String classname) throws ClassNotFoundException {
 		return findClass(classname);
 	}

 	/**
 	 * Closes this class loader.  After this method is called
 	 * loadClass will always throw ClassNotFoundException,
 	 * getResource, getResourceAsStream, and getResources will
 	 * return null.
 	 *
 	 */
 	public void close() {
 		closed = true;
 	}

 	protected ClassLoader getParentPrivileged(){
 		if (System.getSecurityManager() == null)
 			return getParent();

 		return (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
 			public Object run() {
 				return getParent();
 			}
 		});
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2004 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Common Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/cpl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/

	package org.eclipse.osgi.framework.adaptor.core;

	import java.io.IOException;
	import java.net.URL;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import java.security.ProtectionDomain;
	import java.util.Enumeration;

	import org.eclipse.osgi.framework.adaptor.BundleClassLoader;
	import org.eclipse.osgi.framework.adaptor.ClassLoaderDelegate;
	import org.eclipse.osgi.framework.adaptor.ImportResourceNotFoundException;
	import org.eclipse.osgi.framework.debug.Debug;

	/**
	* The AbstractClassLoader provides some basic functionality that all
	* BundleClassLoaders must provide. It properly delegates resource and
	* class lookups to a parent classloader and the to a ClassLoaderDelegate.
	*/
	public abstract class AbstractClassLoader extends ClassLoader implements BundleClassLoader {

	/**
	* The delegate used to get classes and resources from. The delegate
	* must always be queried first before the local ClassLoader is searched for
	* a class or resource.
	*/
	protected ClassLoaderDelegate delegate;

	/**
	* The host ProtectionDomain to use to define classes.
	*/
	protected ProtectionDomain hostdomain;

	/**
	* The host classpath entries for this classloader
	*/
	protected String[] hostclasspath;

	/**
	* Indicates this class loader is closed.
	*/
	protected boolean closed = false;

	/**
	* BundleClassLoader constructor.
	* @param delegate The ClassLoaderDelegate for this bundle.
	* @param domain The ProtectionDomain for this bundle.
	* @param parent The parent classloader to use. Must not be null.
	* @param classpath The classpath entries to use for the host.
	*/
	public AbstractClassLoader(ClassLoaderDelegate delegate, ProtectionDomain domain, String[] classpath, ClassLoader parent) {
	super(parent);
	this.delegate = delegate;
	this.hostdomain = domain;
	this.hostclasspath = classpath;
	}

	/**
	* Loads a class for the bundle. First delegate.findClass(name) is called.
	* The delegate will query the system class loader, bundle imports, bundle
	* local classes, bundle hosts and fragments. The delegate will call
	* BundleClassLoader.findLocalClass(name) to find a class local to this
	* bundle.
	* @param name the name of the class to load.
	* @param resolve indicates whether to resolve the loaded class or not.
	* @return The Class object.
	* @throws ClassNotFoundException if the class is not found.
	*/
	protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
	if (closed)
	throw new ClassNotFoundException(name);

	if (Debug.DEBUG && Debug.DEBUG_LOADER)
	Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ")");

	try {
	// First check the parent classloader for system classes.
	ClassLoader parent = getParentPrivileged();
	if (parent != null)
	try {
	return parent.loadClass(name);
	} catch (ClassNotFoundException e) {
	// Do nothing. continue to delegate.
	}

	// Just ask the delegate. This could result in findLocalClass(name) being called.
	Class clazz = delegate.findClass(name);
	// resolve the class if asked to.
	if (resolve)
	resolveClass(clazz);
	return (clazz);
	} catch (Error e) {
	if (Debug.DEBUG && Debug.DEBUG_LOADER) {
	Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ") failed.");
	Debug.printStackTrace(e);
	}
	throw e;
	} catch (ClassNotFoundException e) {
	// If the class is not found do not try to look for it locally.
	// The delegate would have already done that for us.
	if (Debug.DEBUG && Debug.DEBUG_LOADER) {
	Debug.println("BundleClassLoader[" + delegate + "].loadClass(" + name + ") failed.");
	Debug.printStackTrace(e);
	}
	throw e;
	}
	}

	/**
	* Finds a class local to this bundle. The bundle class path is used
	* to search for the class. The delegate must not be used. This method
	* is abstract to force extending classes to implement this method instead
	* of using the ClassLoader.findClass(String) method.
	* @param name The classname of the class to find
	* @return The Class object.
	* @throws ClassNotFoundException if the class is not found.
	*/
	abstract protected Class findClass(String name) throws ClassNotFoundException;

	/**
	* Gets a resource for the bundle. First delegate.findResource(name) is
	* called. The delegate will query the system class loader, bundle imports,
	* bundle local resources, bundle hosts and fragments. The delegate will
	* call BundleClassLoader.findLocalResource(name) to find a resource local
	* to this bundle.
	* @param name The resource path to get.
	* @return The URL of the resource or null if it does not exist.
	*/
	public URL getResource(String name) {
	if (closed) {
	return null;
	}
	if (Debug.DEBUG && Debug.DEBUG_LOADER) {
	Debug.println("BundleClassLoader[" + delegate + "].getResource(" + name + ")");
	}

	try {
	URL url = null;
	// First check the parent classloader for system resources.
	ClassLoader parent = getParentPrivileged();
	if (parent != null)
	url = parent.getResource(name);
	if (url != null) {
	return (url);
	}
	url = delegate.findResource(name);
	if (url != null) {
	return (url);
	}
	} catch (ImportResourceNotFoundException e) {
	}

	if (Debug.DEBUG && Debug.DEBUG_LOADER) {
	Debug.println("BundleClassLoader[" + delegate + "].getResource(" + name + ") failed.");
	}

	return (null);
	}

	/**
	* Finds a resource local to this bundle. Simply calls
	* findResourceImpl(name) to find the resource.
	* @param name The resource path to find.
	* @return The URL of the resource or null if it does not exist.
	*/
	abstract protected URL findResource(String name);

	/**
	* Finds all resources with the specified name. This method must call
	* delegate.findResources(name) to find all the resources.
	* @param name The resource path to find.
	* @return An Enumeration of all resources found or null if the resource.
	*/
	protected Enumeration findResources(String name) throws IOException {
	try {
	return (delegate.findResources(name));
	} catch (Exception e) {
	if (Debug.DEBUG && Debug.DEBUG_LOADER) {
	Debug.println("BundleClassLoader[" + delegate + "].findResources(" + name + ") failed.");
	Debug.printStackTrace(e);
	}
	return null;
	}
	}

	/**
	* Finds a library for this bundle. Simply calls
	* delegate.findLibrary(libname) to find the library.
	* @param libname The library to find.
	* @return The URL of the resource or null if it does not exist.
	*/
	protected String findLibrary(String libname) {
	return delegate.findLibrary(libname);
	}

	/**
	* Finds a local resource in the BundleClassLoader without
	* consulting the delegate.
	* @param resource the resource path to find.
	* @return a URL to the resource or null if the resource does not exist.
	*/
	public URL findLocalResource(String resource) {
	return findResource(resource);
	}

	/**
	* Finds a local class in the BundleClassLoader without
	* consulting the delegate.
	* @param classname the classname to find.
	* @return The class object found.
	* @throws ClassNotFoundException if the classname does not exist locally.
	*/
	public Class findLocalClass(String classname) throws ClassNotFoundException {
	return findClass(classname);
	}

	/**
	* Closes this class loader. After this method is called
	* loadClass will always throw ClassNotFoundException,
	* getResource, getResourceAsStream, and getResources will
	* return null.
	*
	*/
	public void close() {
	closed = true;
	}

	protected ClassLoader getParentPrivileged(){
	if (System.getSecurityManager() == null)
	return getParent();

	return (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
	public Object run() {
	return getParent();
	}
	});
	}
	}