深入掌握JMS（四）：实战Queue[转]

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。