Queue實現的是點到點模型,在下面的例子中,啓動2個消費者共同監聽一個Queue,然後循環給這個Queue中發送多個消息,我們依然採用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();
- //創建一個Queue
- Queue queue = new ActiveMQQueue("testQueue");
- //創建一個Session
- Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
- //註冊消費者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();
- }
- }
- });
- //註冊消費者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();
- }
- }
- });
- //創建一個生產者,然後發送多個消息。
- MessageProducer producer = session.createProducer(queue);
- for(int i=0; i<10; i++){
- producer.send(session.createTextMessage("Message:" + i));
- }
- }
- }
運行這個例子會得到下面的輸出結果:
- 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
可以看出每個消息直被消費了一次,但是如果有多個消費者同時監聽一個Queue的話,無法確定一個消息最終會被哪一個消費者消費。