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/*
* 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.subscriber;
import org.apache.log4j.Logger;
import org.apache.qpid.client.AMQConnection;
import javax.jms.*;
import org.apache.qpid.example.shared.Statics;
import org.apache.qpid.example.shared.ConnectionException;
import java.net.InetAddress;
/**
* Subscriber which consumes messages from a queue
* Author: Marnie McCormack
* Date: 12-Sep-2006
* Time: 09:41:07
* Copyright JPMorgan Chase 2006
*/
public class Subscriber
{
private static final Logger _logger = Logger.getLogger(Subscriber.class);
protected static Connection _connection;
protected static MessageConsumer _consumer;
protected static Session _session;
/*
* Listener class that handles messages
*/
public static class AMSMessageListener implements MessageListener
{
private String _name;
public AMSMessageListener(String name)
{
_name = name;
}
/*
* Listens for message callbacks, handles and then acknowledges them
* @param message - the message received
*/
public void onMessage(javax.jms.Message message)
{
_logger.info(_name + " got message '" + message + "'");
try
{
//@TODO handle your message appropriately for your application here ?
_logger.debug("Acknowledging recieved message");
//Now acknowledge the message to clear it from our queue
message.acknowledge();
}
catch(JMSException j)
{
_logger.error("JMSException trying to acknowledge message receipt");
j.printStackTrace();
}
catch(Exception e)
{
_logger.error("Unexpected exception trying to handle message");
e.printStackTrace();
}
}
}
/*
* Subscribes to AMS Queue and attaches listener
* @param hostdetails - for broker connection in host1:port1;host2:port2 format
* @param username - for connection to the broker
* @password - for connection to the broker
* @virtualpath
*/
public void subscribe(String hostdetails, String username, String password,
String virtualPath, String queue)
{
Queue q;
_logger.info("Starting subscription ...");
try
{
//To enable failover simply specify more than one host:port combination for hostdetails
//Format is host1:port1;host2:port2
_connection = getConnectionWithFailover(hostdetails,username,password,virtualPath);
//Default to a queue with a default name if queue is null - replace with your own name from config etc
if (queue==null || queue.length()==0)
{
q = getSession(_connection).createQueue(Statics.QUEUE_NAME);
}
else
{
q = getSession(_connection).createQueue(queue);
}
//Create a consumer with a destination of our queue which will use defaults for prefetch etc
_consumer = getSession(_connection).createConsumer(q);
//give the message listener a name of it's own
_consumer.setMessageListener(new AMSMessageListener("MessageListener " + System.currentTimeMillis()));
_connection.start();
}
catch (Throwable t)
{
_logger.error("Fatal error: " + t);
t.printStackTrace();
}
_logger.info("Waiting for messages ...");
//wait for messages and sleep to survive failover
try
{
while(true)
{
Thread.sleep(Long.MAX_VALUE);
}
}
catch (Exception e)
{
_logger.warn("Exception while Subscriber sleeping",e);
}
}
/*
* stop consuming and close connection
*/
public void stop()
{
try
{
_consumer.close();
_consumer = null;
_connection.stop();
_connection.close();
}
catch(JMSException j)
{
_logger.error("JMSException trying to Subscriber.stop: " + j.getStackTrace());
}
}
/*
* Get a connection for our broker with failover by providing an array of hostdetails
* @param hostdetails - a delimited string of host1:port1;host2:port2 style connection details
* @param username - for connection to the broker
* @password - for connection to the broker
* @virtualpath
*/
protected Connection getConnectionWithFailover(String hostdetails, String username, String password,
String virtualPath) throws ConnectionException
{
if (_connection == null)
{
try
{
_connection = new AMQConnection(hostdetails,username,password,InetAddress.getLocalHost().getHostName(),virtualPath);
//To use a url to get your connection create a string in this format and then get a connection with it
//String myurl = "amqp://guest:guest@/temp?brokerlist='tcp://localhost:5672',failover='roundrobin'";
//_connection = new AMQConnectionFactory(url).createConnection();
return _connection;
}
catch (Exception e)
{
throw new ConnectionException(e.toString());
}
}
else
{
return _connection;
}
}
/*
* Creates a non-transacted session for consuming messages
* Using client acknowledge mode means messages removed from queue only once ack'd
* @param connection - to the broker
*/
protected Session getSession(Connection connection) throws JMSException
{
if (_session == null)
{
_session = connection.createSession(false, Session.CLIENT_ACKNOWLEDGE);
return _session;
}
else
{
return _session;
}
}
}
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