深入掌握JMS（五）：实战Topic

左手的ㄟ右手 2022-08-13 11:52 95阅读 0赞

与Queue不同的是，Topic实现的是发布/订阅模型，在下面的例子中，启动2个消费者共同监听一个Topic，然后循环给这个Topic中发送多个消息。  
  
import javax.jms.Connection; import javax.jms.JMSException; import javax.jms.Message; import javax.jms.MessageConsumer; import javax.jms.MessageListener; import javax.jms.MessageProducer; import javax.jms.Session; import javax.jms.TextMessage; import javax.jms.Topic; import org.apache.activemq.ActiveMQConnectionFactory; import org.apache.activemq.command.ActiveMQTopic; public class TopicTest \{ public static void main(String\[\] args) throws Exception \{ ActiveMQConnectionFactory factory = new ActiveMQConnectionFactory("vm://localhost"); Connection connection = factory.createConnection(); connection.start(); //创建一个Topic Topic topic= new ActiveMQTopic("testTopic"); Session session = connection.createSession(false, Session.AUTO\_ACKNOWLEDGE); //注册消费者1 MessageConsumer comsumer1 = session.createConsumer(topic); 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(topic); 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(topic); for(int i=0; i<10; i++)\{ producer.send(session.createTextMessage("Message:" + i)); \} \} \}  
运行后得到下面的输出结果：  
  
Consumer1 get Message:0 Consumer2 get Message:0 Consumer1 get Message:1 Consumer2 get Message:1 Consumer1 get Message:2 Consumer2 get Message:2 Consumer1 get Message:3 Consumer2 get Message:3 Consumer1 get Message:4 Consumer2 get Message:4 Consumer1 get Message:5 Consumer2 get Message:5 Consumer1 get Message:6 Consumer2 get Message:6 Consumer1 get Message:7 Consumer2 get Message:7 Consumer1 get Message:8 Consumer2 get Message:8 Consumer1 get Message:9 Consumer2 get Message:9  
说明每一个消息都会被所有的消费者消费。