Jdk13ProxyFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.openejb.util.proxy;

import org.apache.openejb.OpenEJBException;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.util.LinkedHashSet;
import java.util.Properties;
import java.util.Set;

/**
 * @org.apache.xbean.XBean
 */
public class Jdk13ProxyFactory implements ProxyFactory {

    public void init(final Properties props) throws OpenEJBException {
    }

    public InvocationHandler getInvocationHandler(final Object proxy) throws IllegalArgumentException {
        return (InvocationHandler) Proxy.getInvocationHandler(proxy);
    }

    public Class getProxyClass(final Class interfce) throws IllegalArgumentException {
        return Proxy.getProxyClass(interfce.getClassLoader(), new Class[]{interfce});
    }

    public Class getProxyClass(final Class[] interfaces) throws IllegalArgumentException {
        if (interfaces.length < 1) {
            throw new IllegalArgumentException("It's boring to implement 0 interfaces!");
        }
        return Proxy.getProxyClass(interfaces[0].getClassLoader(), interfaces);
    }

    /*
     * Returns true if and only if the specified class was dynamically generated to be a proxy class using the getProxyClass method or the newProxyInstance method.
     */
    public boolean isProxyClass(final Class cl) {
        return Proxy.isProxyClass(cl);
    }

    /*
     * Returns an instance of a proxy class for the specified interface that dispatches method invocations to
     * the specified invocation handler.
     */
    public Object newProxyInstance(final Class interfce, final InvocationHandler h) throws IllegalArgumentException {
        try {
            return Proxy.newProxyInstance(interfce.getClassLoader(), new Class[]{interfce}, h);
        } catch (final IllegalArgumentException iae) {
            final ClassLoader reconciliatedCl = reconciliate(interfce);
            try {
                reconciliatedCl.loadClass(interfce.getName());
                return Proxy.newProxyInstance(reconciliatedCl, new Class[]{interfce}, h);
            } catch (final ClassNotFoundException e2) {
                throw iae;
            }
        }
    }

    /*
     * Returns an instance of a proxy class for the specified interface that dispatches method invocations to
     * the specified invocation handler.
     */
    public Object newProxyInstance(final Class[] interfaces, final InvocationHandler handler) throws IllegalArgumentException {
        if (interfaces.length < 1) {
            throw new IllegalArgumentException("It's boring to implement 0 interfaces!");
        }

        try {
            return Proxy.newProxyInstance(interfaces[0].getClassLoader(), interfaces, handler);
        } catch (final IllegalArgumentException e) {
            final ClassLoader tccl = Thread.currentThread().getContextClassLoader();
            try {
                final Class tcclHomeClass = tccl.loadClass(interfaces[0].getName());
                if (tcclHomeClass == interfaces[0]) {
                    return Proxy.newProxyInstance(tccl, interfaces, handler);
                }
            } catch (final ClassNotFoundException e1) {
                // maybe all interfaces are not in the same classloader (OSGi)
                // trying to reconciliate it here
                final ClassLoader reconciliatedCl = reconciliate(interfaces);
                final Class homeClass;
                try {
                    homeClass = reconciliatedCl.loadClass(interfaces[0].getName());
                    if (homeClass == interfaces[0]) {
                        return Proxy.newProxyInstance(reconciliatedCl, interfaces, handler);
                    }
                } catch (final ClassNotFoundException e2) {
                    throw e;
                }
            }
            throw e;
        }
    }

    private static ClassLoader reconciliate(final Class<?>... interfaces) {
        final Set<ClassLoader> classloaders = new LinkedHashSet<ClassLoader>();
        for (final Class<?> clazz : interfaces) {
            classloaders.add(clazz.getClassLoader());
        }
        return new MultipleClassLoadersClassLoader(classloaders.toArray(new ClassLoader[classloaders.size()]));
    }

    private static class MultipleClassLoadersClassLoader extends ClassLoader {
        private final ClassLoader[] delegatingClassloaders;

        public MultipleClassLoadersClassLoader(final ClassLoader[] classLoaders) {
            super(classLoaders[0]);
            delegatingClassloaders = classLoaders;
        }

        @Override
        public Class<?> loadClass(final String name) throws ClassNotFoundException {
            ClassNotFoundException ex = null;
            for (final ClassLoader cl : delegatingClassloaders) {
                try {
                    return cl.loadClass(name);
                } catch (final ClassNotFoundException cnfe) {
                    if (ex == null) {
                        ex = cnfe;
                    }
                }
            }
            throw ex;
        }
    }
}