001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.commons.jcs.jcache.proxy;
020
021import java.lang.reflect.Constructor;
022import java.lang.reflect.InvocationHandler;
023import java.lang.reflect.InvocationTargetException;
024import java.lang.reflect.Method;
025import java.lang.reflect.Proxy;
026
027public class ExceptionWrapperHandler<T> implements InvocationHandler
028{
029    private final T delegate;
030    private final Constructor<? extends RuntimeException> wrapper;
031
032    public ExceptionWrapperHandler(final T delegate, final Class<? extends RuntimeException> exceptionType)
033    {
034        this.delegate = delegate;
035        try
036        {
037            this.wrapper = exceptionType.getConstructor(Throwable.class);
038        }
039        catch (final NoSuchMethodException e)
040        {
041            throw new IllegalStateException(e);
042        }
043    }
044
045    @Override
046    public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable
047    {
048        try
049        {
050            return method.invoke(delegate, args);
051        }
052        catch (final InvocationTargetException ite)
053        {
054            final Throwable e = ite.getCause();
055            if (RuntimeException.class.isInstance(e))
056            {
057                final RuntimeException re;
058                try
059                {
060                    re = wrapper.newInstance(e);
061                }
062                catch (final Exception e1)
063                {
064                    throw new IllegalArgumentException(e1);
065                }
066                throw re;
067            }
068            throw e;
069        }
070    }
071
072    public static <T> T newProxy(final ClassLoader loader, final T delegate, final Class<? extends RuntimeException> exceptionType,
073            final Class<T> apis)
074    {
075        return (T) Proxy.newProxyInstance(loader, new Class<?>[] { apis }, new ExceptionWrapperHandler<T>(delegate, exceptionType));
076    }
077}