RC9/qpid/java/client/example/src/main/java/org/apache/qpid/example/jmsexample/fanout/Listener.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.qpid.example.jmsexample.fanout;

import java.util.Properties;

import javax.jms.*;
import javax.naming.Context;
import javax.naming.InitialContext;

/**
 * The example creates a MessageConsumer on the specified
 * Queue and uses a MessageListener with this MessageConsumer
 * in order to enable asynchronous delivery.
 */
public class Listener implements MessageListener
{
    /* Used in log output. */
    private static final String CLASS = "Listener";

    /**
     * An object to synchronize on.
     */
    private final Object _lock = new Object();

    /**
     * A boolean to indicate a clean finish.
     */
    private boolean _finished = false;

    /**
     * A boolean to indicate an unsuccesful finish.
     */
    private boolean _failed = false;



    /**
     * Run the message consumer example.
     *
     * @param args Command line arguments.
     */
    public static void main(String[] args) throws Exception
    {
        if (args.length == 0)
        {
            throw new Exception("You need to specify the JNDI name for the queue");
        }
        Listener listener = new Listener();
        listener.runTest(args[0]);
    }

    /**
     * Start the example.
     */
    private void runTest(String queueName)
    {
        try
        {
            Properties properties = new Properties();
            properties.load(this.getClass().getResourceAsStream("fanout.properties"));

            //Create the initial context
            Context ctx = new InitialContext(properties);

            Destination destination = (Destination)ctx.lookup(queueName);

            // Declare the connection
            ConnectionFactory conFac = (ConnectionFactory)ctx.lookup("qpidConnectionfactory");
            Connection connection = conFac.createConnection();

            // As this application is using a MessageConsumer we need to set an ExceptionListener on the connection
            // so that errors raised within the JMS client library can be reported to the application
            System.out.println(
                    CLASS + ": Setting an ExceptionListener on the connection as sample uses a MessageConsumer");

            connection.setExceptionListener(new ExceptionListener()
            {
                public void onException(JMSException jmse)
                {
                    // The connection may have broken invoke reconnect code if available.
                    System.err.println(CLASS + ": The sample received an exception through the ExceptionListener");
                    System.exit(0);
                }
            });

            // Create a session on the connection
            // This session is a default choice of non-transacted and uses
            // the auto acknowledge feature of a session.
            System.out.println(CLASS + ": Creating a non-transacted, auto-acknowledged session");

            Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);

            // Create a MessageConsumer
            System.out.println(CLASS + ": Creating a MessageConsumer");

            MessageConsumer messageConsumer = session.createConsumer(destination);

            // Set a message listener on the messageConsumer
            messageConsumer.setMessageListener(this);

            // Now the messageConsumer is set up we can start the connection
            System.out.println(CLASS + ": Starting connection so MessageConsumer can receive messages");
            connection.start();

            // Wait for the messageConsumer to have received all the messages it needs
            synchronized (_lock)
            {
                while (!_finished && !_failed)
                {
                    _lock.wait();
                }
            }

            // If the MessageListener abruptly failed (probably due to receiving a non-text message)
            if (_failed)
            {
                System.out.println(CLASS + ": This sample failed as it received unexpected messages");
            }

            // Close the connection to the server
            System.out.println(CLASS + ": Closing connection");
            connection.close();

            // Close the JNDI reference
            System.out.println(CLASS + ": Closing JNDI context");
            ctx.close();
        }
        catch (Exception exp)
        {
            System.err.println(CLASS + ": Caught an Exception: " + exp);
        }
    }

    /**
     * This method is required by the <CODE>MessageListener</CODE> interface. It
     * will be invoked  when messages are available.
     * After receiving the finish message (That's all, folks!) it releases a lock so that the
     * main program may continue.
     *
     * @param message The message.
     */
    public void onMessage(Message message)
    {
        try
        {
            String text;
            if (message instanceof TextMessage)
            {
                text = ((TextMessage) message).getText();
            }
            else
            {
                byte[] body = new byte[(int) ((BytesMessage) message).getBodyLength()];
                ((BytesMessage) message).readBytes(body);
                text = new String(body);
            }
            if (text.equals("That's all, folks!"))
            {
                System.out.println(CLASS + ": Received final message " + text);
                synchronized (_lock)
                {
                    _finished = true;
                    _lock.notifyAll();
                }
            }
            else
            {
                System.out.println(CLASS + ": Received  message:  " + text);
            }
        }
        catch (JMSException exp)
        {
            System.out.println(CLASS + ": Caught an exception handling a received message");
            exp.printStackTrace();
            synchronized (_lock)
            {
                _failed = true;
                _lock.notifyAll();
            }
        }
    }
}