| /* |
| * 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.qpid.client.AMQConnectionFactory; |
| |
| import javax.jms.*; |
| import javax.jms.Connection; |
| import javax.jms.MessageConsumer; |
| import javax.jms.Session; |
| import javax.naming.InitialContext; |
| |
| import org.apache.qpid.example.shared.InitialContextHelper; |
| import org.slf4j.LoggerFactory; |
| import org.slf4j.Logger; |
| |
| /** |
| * Subscriber which consumes messages from a queue |
| */ |
| |
| public class Subscriber |
| { |
| private static final Logger _log = LoggerFactory.getLogger(Subscriber.class); |
| |
| protected static Connection _connection; |
| |
| protected static MessageConsumer _consumer; |
| |
| protected static InitialContextHelper _contextHelper; |
| |
| protected static AMQConnectionFactory _connectionFactory; |
| |
| protected Destination _destination; |
| |
| public Subscriber() |
| { |
| try |
| { |
| //get an initial context from default properties |
| _contextHelper = new InitialContextHelper(null); |
| InitialContext ctx = _contextHelper.getInitialContext(); |
| |
| //then create a connection using the AMQConnectionFactory |
| _connectionFactory = (AMQConnectionFactory) ctx.lookup("local"); |
| |
| //lookup queue from context |
| _destination = (Destination) ctx.lookup("MyQueue"); |
| |
| } |
| catch (Exception e) |
| { |
| e.printStackTrace(); |
| _log.error("Exception", e); |
| } |
| } |
| |
| /** |
| * Listener class that handles messages |
| */ |
| public static class ExampleMessageListener implements MessageListener |
| { |
| private String _name; |
| |
| public ExampleMessageListener(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) |
| { |
| _log.info(_name + " got message '" + message + "'"); |
| |
| try |
| { |
| //NB: Handle your message appropriately for your application here |
| //do some stuff |
| |
| _log.debug("Acknowledging recieved message"); |
| |
| //Now acknowledge the message to clear it from our queue |
| message.acknowledge(); |
| } |
| catch(JMSException j) |
| { |
| _log.error("JMSException trying to acknowledge message receipt"); |
| j.printStackTrace(); |
| } |
| catch(Exception e) |
| { |
| _log.error("Unexpected exception trying to handle message"); |
| e.printStackTrace(); |
| } |
| } |
| } |
| |
| /** |
| * Subscribes to example Queue and attaches listener |
| */ |
| public void subscribe() |
| { |
| _log.info("Starting subscription ..."); |
| |
| try |
| { |
| _connection = _connectionFactory.createConnection(); |
| |
| //Non transactional session using client acknowledgement |
| Session session = _connection.createSession(false, Session.CLIENT_ACKNOWLEDGE); |
| |
| //Create a consumer with a destination of our queue which will use defaults for prefetch etc |
| _consumer = session.createConsumer(_destination); |
| |
| //give the message listener a name of it's own |
| _consumer.setMessageListener(new ExampleMessageListener("MessageListener " + System.currentTimeMillis())); |
| |
| _connection.start(); |
| } |
| catch (Throwable t) |
| { |
| _log.error("Fatal error: " + t); |
| t.printStackTrace(); |
| } |
| |
| _log.info("Waiting for messages ..."); |
| |
| //wait for messages and sleep to survive failover |
| try |
| { |
| while(true) |
| { |
| Thread.sleep(Long.MAX_VALUE); |
| } |
| } |
| catch (Exception e) |
| { |
| _log.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) |
| { |
| _log.error("JMSException trying to Subscriber.stop: " + j.getStackTrace()); |
| } |
| } |
| |
| } |
| |
| |
| |
| |