DelegatingClassLoader.java |
/*************************************** * * * JBoss: The OpenSource J2EE WebOS * * * * Distributable under LGPL license. * * See terms of license at gnu.org. * * * ***************************************/ package org.jboss.util.loading; import java.net.URL; import java.net.URLClassLoader; import java.net.URLStreamHandlerFactory; /** * A URL classloader that delegates to its parent, avoiding * synchronization. * * A standard flag is provided so it can be used as a parent class, * but later subclassed and to revert to standard class loading * if the subclass wants to load classes. * * @author <a href="mailto:adrian@jboss.org">Adrian Brock</a> * @version $Revision: 1.2 $ */ public class DelegatingClassLoader extends URLClassLoader { /** The value returned by {@link getURLs}. */ public static final URL[] EMPTY_URL_ARRAY = {}; /** Whether to use standard loading */ protected boolean standard = false; /** * Constructor * * @param parent the parent classloader, cannot be null. */ public DelegatingClassLoader(ClassLoader parent) { super(EMPTY_URL_ARRAY, parent); if (parent == null) throw new IllegalArgumentException("No parent"); } /** * Constructor * * @param parent, the parent classloader, cannot be null. * @param factory the url stream factory. */ public DelegatingClassLoader(ClassLoader parent, URLStreamHandlerFactory factory) { super(EMPTY_URL_ARRAY, parent, factory); if (parent == null) throw new IllegalArgumentException("No parent"); } /** * Load a class, by asking the parent * * @param className the class name to load * @param resolve whether to link the class * @return the loaded class * @throws ClassNotFoundException when the class could not be found */ protected Class loadClass(String className, boolean resolve) throws ClassNotFoundException { // Revert to standard rules if (standard) return super.loadClass(className, resolve); // Ask the parent Class clazz = getParent().loadClass(className); // Link the class if (resolve) resolveClass(clazz); return clazz; } }
DelegatingClassLoader.java |