深入掌握JMS（四）：实战Queue

￡神魔★判官ぃ 2022-08-13 11:52 111阅读 0赞

Queue实现的是点到点模型，在下面的例子中，启动2个消费者共同监听一个Queue，然后循环给这个Queue中发送多个消息，我们依然采用ActiveMQ。

import javax.jms.Connection; import javax.jms.DeliveryMode; import javax.jms.JMSException; import javax.jms.Message; import javax.jms.MessageConsumer; import javax.jms.MessageListener; import javax.jms.MessageProducer; import javax.jms.Queue; import javax.jms.Session; import javax.jms.TextMessage; import org.apache.activemq.ActiveMQConnectionFactory; import org.apache.activemq.command.ActiveMQQueue; public class QueueTest \{ public static void main(String\[\] args) throws Exception \{ ActiveMQConnectionFactory factory = new ActiveMQConnectionFactory("vm://localhost"); Connection connection = factory.createConnection(); connection.start(); //创建一个Queue Queue queue = new ActiveMQQueue("testQueue"); //创建一个Session Session session = connection.createSession(false, Session.AUTO\_ACKNOWLEDGE); //注册消费者1 MessageConsumer comsumer1 = session.createConsumer(queue); comsumer1.setMessageListener(new MessageListener()\{ public void onMessage(Message m) \{ try \{ System.out.println("Consumer1 get " + ((TextMessage)m).getText()); \} catch (JMSException e) \{ e.printStackTrace(); \} \} \}); //注册消费者2 MessageConsumer comsumer2 = session.createConsumer(queue); comsumer2.setMessageListener(new MessageListener()\{ public void onMessage(Message m) \{ try \{ System.out.println("Consumer2 get " + ((TextMessage)m).getText()); \} catch (JMSException e) \{ e.printStackTrace(); \} \} \}); //创建一个生产者，然后发送多个消息。 MessageProducer producer = session.createProducer(queue); for(int i=0; i<10; i++)\{ producer.send(session.createTextMessage("Message:" + i)); \} \} \}

运行这个例子会得到下面的输出结果：

Consumer1 get Message:0 Consumer2 get Message:1 Consumer1 get Message:2 Consumer2 get Message:3 Consumer1 get Message:4 Consumer2 get Message:5 Consumer1 get Message:6 Consumer2 get Message:7 Consumer1 get Message:8 Consumer2 get Message:9  
可以看出每个消息直被消费了一次，但是如果有多个消费者同时监听一个Queue的话，无法确定一个消息最终会被哪一个消费者消费。