001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.examples.impl;
016    
017    import java.lang.reflect.InvocationHandler;
018    import java.lang.reflect.InvocationTargetException;
019    import java.lang.reflect.Method;
020    
021    import org.apache.commons.logging.Log;
022    import org.apache.hivemind.service.impl.LoggingUtils;
023    
024    /**
025     * An invocation handler used by {@link org.apache.examples.impl.ProxyLoggingInterceptorFactory}.
026     * Logs all method invocations, return values and exceptions.  Note that, unlike the real
027     * LoggingInterceptor, <code>toString()</code> will just pass through to the delegate service object
028     * (typically, the core service implementation).
029     *
030     * @author Howard Lewis Ship
031     */
032    public class ProxyLoggingInvocationHandler implements InvocationHandler
033    {
034        private Log _log;
035        private Object _delegate;
036    
037        public ProxyLoggingInvocationHandler(Log log, Object delegate)
038        {
039            _log = log;
040            _delegate = delegate;
041        }
042    
043        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
044        {
045            boolean debug = _log.isDebugEnabled();
046    
047            if (debug)
048                LoggingUtils.entry(_log, method.getName(), args);
049    
050            try
051            {
052                Object result = method.invoke(_delegate, args);
053    
054                if (debug)
055                {
056                    if (method.getReturnType() == void.class)
057                        LoggingUtils.voidExit(_log, method.getName());
058                    else
059                        LoggingUtils.exit(_log, method.getName(), result);
060                }
061    
062                return result;
063            }
064            catch (InvocationTargetException ex)
065            {
066                Throwable targetException = ex.getTargetException();
067    
068                if (debug)
069                    LoggingUtils.exception(_log, method.getName(), targetException);
070    
071                throw targetException;
072            }
073        }
074    
075    }