001 /**
002 *
003 * Copyright 2004 Protique Ltd
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 **/
018 package org.activemq.util;
019
020 import javax.jms.ExceptionListener;
021 import javax.jms.JMSException;
022 import javax.jms.Message;
023 import javax.jms.MessageListener;
024
025 /**
026 * A helper base class which makes writing message listeners easier without
027 * having to worry about handling the JMSException on the onMessage() method.
028 * By default the JMS ExceptionListener will be used to handle any JMS exceptions
029 * or if none is configured then a runtime exception will be generated.
030 *
031 * @author James Strachan
032 * @version $Revision: 1.1.1.1 $
033 */
034 public abstract class MessageListenerSupport implements MessageListener {
035 private ExceptionListener exceptionListener;
036
037 public void onMessage(Message message) {
038 try {
039 processMessage(message);
040 }
041 catch (JMSException e) {
042 onJMSException(e, message);
043 }
044 catch (Exception e) {
045 // lets wrap the exception
046 JMSException jmsEx = JMSExceptionHelper.newJMSException(e.getMessage(), e);
047 onJMSException(jmsEx, message);
048 }
049 }
050
051 public ExceptionListener getExceptionListener() {
052 return exceptionListener;
053 }
054
055 public void setExceptionListener(ExceptionListener exceptionListener) {
056 this.exceptionListener = exceptionListener;
057 }
058
059 /**
060 * This method processes the incoming message possibly throwing a JMSException
061 * if the message could not be processed correctly.
062 *
063 * @param messsage
064 * @throws Exception
065 */
066 protected abstract void processMessage(Message messsage) throws Exception;
067
068 /**
069 * Process the JMS exception either by calling an exception listener
070 * which can contian custom logic or by throwing a runtime exception
071 *
072 * @param e
073 * @param message
074 */
075 protected void onJMSException(JMSException e, Message message) {
076 if (exceptionListener != null) {
077 exceptionListener.onException(e);
078 }
079 else {
080 throw new RuntimeException("Failed to process message: " + message + " Reason: " + e, e);
081 }
082 }
083
084 }