001 /*
002 * Copyright (C) The Apache Software Foundation. All rights reserved.
003 *
004 * This software is published under the terms of the Apache Software License
005 * version 1.1, a copy of which has been included with this distribution in
006 * the LICENSE file.
007 *
008 * $Id: Consumer.java 155459 2005-02-26 13:24:44Z dirkv $
009 */
010 package org.apache.commons.messenger.tool;
011
012 import java.io.FileWriter;
013 import java.io.OutputStreamWriter;
014 import java.io.PrintWriter;
015 import java.io.Writer;
016
017 import javax.jms.Destination;
018 import javax.jms.JMSException;
019 import javax.jms.Message;
020 import javax.jms.TextMessage;
021
022 import org.apache.commons.messenger.Messenger;
023 import org.apache.commons.messenger.MessengerManager;
024
025 /** <p><code>Consumer</code> is a sample program that
026 * consumes a single message and either writes it to
027 * either stanard output or a named file.</p>
028 *
029 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
030 * @version $Revision: 155459 $
031 */
032 public class Consumer {
033
034 private Messenger messenger;
035
036 public static void main(String[] args) {
037 try {
038 Consumer client = new Consumer();
039 client.run( args );
040 }
041 catch (JMSException e) {
042 System.out.println( "Caught: " + e );
043 Exception linked = e.getLinkedException();
044 if ( linked != null ) {
045 System.out.println( "Underlying exception: " + linked );
046 linked.printStackTrace();
047 }
048 else {
049 e.printStackTrace();
050 }
051 }
052 catch (Exception e) {
053 System.out.println( "Caught: " + e );
054 e.printStackTrace();
055 }
056 }
057
058 public void run(String[] args) throws Exception {
059 if ( args.length < 2 ) {
060 System.out.println( "Usage: Consumer messengerName destination [fileName]" );
061 System.out.println( "If no fileName is provided then the current input stream is used" );
062 return;
063 }
064 String name = args[0];
065 String subject = args[1];
066 messenger = MessengerManager.get( name );
067 if ( messenger == null ) {
068 throw new JMSException( "No such messenger called: " + name );
069 }
070 Destination destination = messenger.getDestination( subject );
071 if ( destination == null ) {
072 throw new JMSException( "Could not find destination: " + subject );
073 }
074
075 Writer writer = ( args.length > 2 )
076 ? new FileWriter( args[2] )
077 : new OutputStreamWriter( System.out );
078
079 Message message = messenger.receive( destination );
080
081 writeMessage( message, writer );
082
083 // close the JMS connection to release any background threads
084 messenger.close();
085 }
086
087 /** Writes the given message to the Writer */
088 protected void writeMessage(Message message, Writer out) throws Exception {
089 PrintWriter writer = new PrintWriter(out);
090 if ( message instanceof TextMessage ) {
091 TextMessage textMessage = (TextMessage) message;
092 writer.println( textMessage.getText() );
093 }
094 writer.close();
095 }
096 }
097
098