activemq-queue-MessageListener

其他相关文章：
http://wangxinchun.iteye.com/blog/2145998
http://wangxinchun.iteye.com/blog/2145958

activemq 中消费者获取消息有两种方式：
1、通过MessageConsumer.receive(TIMEOUT) 方法拉消息。
2、通过MessageConsumer.setMessageListener(new MessageListener(){}) 监听消息。

上面的文章都是用的第一种拉消息的方式，在项目中，更方便的做法是第二种，通过设置消息监听器监听消息，由mq broker 推消息过来。

下面的代码演示了监听方式的用法：

public class Consumer {
    private static final String BROKER_URL = "tcp://localhost:61616";
    private static final Boolean NON_TRANSACTED = false;
    private static final long TIMEOUT = 20000;

    public static void main(String[] args) {
        String url = BROKER_URL;
        if (args.length > 0) {
            url = args[0].trim();
        }
        System.out.println("\nWaiting to receive messages... will timeout after " + TIMEOUT / 1000 +"s");
        //MQ 连接工厂对象
        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("admin", "password", url);
        Connection connection = null;

        try {

        	//建连接
            connection = connectionFactory.createConnection();
            connection.start();

            //创建会话
            Session session = connection.createSession(NON_TRANSACTED, Session.AUTO_ACKNOWLEDGE);
            Destination destination = session.createQueue("test-queue");
            MessageConsumer consumer = session.createConsumer(destination);
            
            consumer.setMessageListener(new MessageListener(){

				@Override
				public void onMessage(Message message) {
					if(message instanceof TextMessage){
						try {
							System.out.println(((TextMessage)message).getText());
						} catch (JMSException e) {
							e.printStackTrace();
						}
					}
				}
            	
            });
            System.in.read();
            session.close();

        } catch (Exception e) {
            System.out.println("Caught exception!");
        }
        finally {
            if (connection != null) {
                try {
                    connection.close();
                } catch (JMSException e) {
                    System.out.println("Could not close an open connection...");
                }
            }
        }
    }
}