深入掌握JMS（五）：实战Topic

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。