Java tutorial
/* * JBoss, Home of Professional Open Source. * Copyright 2008, Red Hat Middleware LLC, and individual contributors * as indicated by the @author tags. See the copyright.txt file in the * distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This software 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. */ package org.jboss.instrument.classloading; import java.lang.instrument.ClassFileTransformer; import java.lang.reflect.Method; import java.security.AccessController; import java.security.PrivilegedExceptionAction; import org.jboss.classloader.spi.ClassLoaderPolicy; import org.jboss.classloader.spi.base.BaseClassLoader; import org.jboss.util.loading.Translator; import org.springframework.util.Assert; import org.springframework.instrument.classloading.SimpleThrowawayClassLoader; /** * Reflective wrapper around a JBoss5 class loader. Used to * encapsulate the classloader-specific methods (discovered and * called through reflection) from the load-time weaver. * * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a> */ public abstract class JBoss5ClassLoader extends ReflectionHelper { private final BaseClassLoader classLoader; private ClassLoaderPolicy policy; protected JBoss5ClassLoader(BaseClassLoader classLoader) { Assert.notNull(classLoader, "ClassLoader must not be null"); this.classLoader = classLoader; try { SecurityManager sm = System.getSecurityManager(); if (sm != null) { AccessController.doPrivileged(new InstantiationAction()); } else { doInstantiate(); } } catch (Exception e) { throw new IllegalStateException( "Could not initialize JBoss ClassLoader because JBoss5 API classes are not available", e); } } /** * Get the policy. * * @return the policy */ protected ClassLoaderPolicy getPolicy() { return policy; } /** * Do instantiate method, variables. * * @throws Exception for any error */ private void doInstantiate() throws Exception { Method getPolicy = getMethod(BaseClassLoader.class, "getPolicy"); policy = invokeMethod(getPolicy, classLoader, ClassLoaderPolicy.class); fallbackStrategy(); } /** * The fallback strategy. * * @throws Exception for any error */ protected void fallbackStrategy() throws Exception { } public void addTransformer(ClassFileTransformer transformer) { Assert.notNull(transformer, "ClassFileTransformer must not be null"); Translator translator = new ClassFileTransformer2Translator(transformer); addTranslator(translator); } /** * Add the translator. * * @param translator the translator */ protected abstract void addTranslator(Translator translator); public ClassLoader getInternalClassLoader() { return classLoader; } public ClassLoader getThrowawayClassLoader() { return new SimpleThrowawayClassLoader(classLoader); } /** * Instantiation action. */ private class InstantiationAction implements PrivilegedExceptionAction<Object> { public Object run() throws Exception { doInstantiate(); return null; } } }