ActiveMQ集群下的消息回流功能

"丢失"的消息

　　如果有broker1和broker2通过networkConnector连接，有一个consumer1连接到broker1,一个consumer2连接到broker2，程序往broker1上面发送30条消息，这时consumer2连接到broker2消费消息，当consumer2消费了15条消息时，broker2挂掉了。 但是还剩下15条消息在broker2上面，这些消息就好像消息了，除非broker2重启了，然后有消费者连接到broker2上来消费消息，遇到这样的情况该怎么办呢？

　　从5.6版本起，在destinationPolicy上新增的选择replayWhenNoConsumers，这个选项使得broker2上有需要转发的消息但是没有消费者时，把消息回流到它原来的broker1上，同时需要把enableAudit设置为false,为了防止消息回流后被当做重复消息而不被分发，activemq.xml配置如下：

多个broker配置

<policyEntry queue=">" enableAudit="false">

　　 <networkBridgeFilterFactory>

　　　　 <conditionalNetworkBridgeFilterFactory replayWhenNoConsumers="true"/>

　　 </networkBridgeFilterFactory>

</policyEntry>

配置ActiveMQ的静态网络链接

必须写上duplex="true"

<networkConnectors>
     <networkConnector name="local network" duplex="true" uri="static://(tcp://ip:prot,tcp://ip:port)"/>
</networkConnectors>

配置允许双向连接

先运行发送消息程序，然后运行61716端口的程序接收消息，再接收了5条后将程序断掉，再去运行61616端口的程序，也是可以接收消息的，这样就实现了消息的回流。

消息发送程序：

 1 import javax.jms.Connection;
 2 import javax.jms.ConnectionFactory;
 3 import javax.jms.Destination;
 4 import javax.jms.MessageProducer;
 5 import javax.jms.Session;
 6 import javax.jms.TextMessage;
 7 
 8 import org.apache.activemq.ActiveMQConnectionFactory;
 9 
10 public class JmsSend {
11     public static void main(String[] args) throws Exception {
12         ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://192.168.1.81:61616");
13         Connection connection = connectionFactory.createConnection();
14         connection.start();
15         
16         Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
17         Destination destination = session.createQueue("my-queue");
18         
19         MessageProducer producer = session.createProducer(destination);
20         for(int i = 0;i < 10;i++){
21             TextMessage message = session.createTextMessage("message,1212 --->" + i);
22             Thread.sleep(1000);
23             //通过生产者发出消息
24             producer.send(message);
25         }
26         session.commit();
27         session.close();
28         connection.close();
29     }
30 }

 61616端口接收消息程序：

 1 import javax.jms.Connection;
 2 import javax.jms.ConnectionFactory;
 3 import javax.jms.Destination;
 4 import javax.jms.MessageConsumer;
 5 import javax.jms.Session;
 6 import javax.jms.TextMessage;
 7 
 8 import org.apache.activemq.ActiveMQConnectionFactory;
 9 
10 public class JmsReceiver {
11     public static void main(String[] args) throws Exception {
12         ConnectionFactory cf = new ActiveMQConnectionFactory("tcp://192.168.1.81:61616");
13         Connection connection =  cf.createConnection();
14         connection.start();
15         
16         Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
17         Destination destination = session.createQueue("my-queue");
18         MessageConsumer consumer = session.createConsumer(destination);
19         int i = 0;
20         while(i < 10){
21             Thread.sleep(3000);
22             i++;
23             TextMessage message = (TextMessage)consumer.receive();
24             session.commit();
25             System.out.println("111接收到的消息是:"+message.getText());
26         }
27         session.close();
28         connection.close();
29     }
30 }

 61716端口接收消息程序：

 1 import javax.jms.Connection;
 2 import javax.jms.ConnectionFactory;
 3 import javax.jms.Destination;
 4 import javax.jms.MessageConsumer;
 5 import javax.jms.Session;
 6 import javax.jms.TextMessage;
 7 
 8 import org.apache.activemq.ActiveMQConnectionFactory;
 9 
10 public class JmsReceiver2 {
11     public static void main(String[] args) throws Exception {
12         ConnectionFactory cf = new ActiveMQConnectionFactory("tcp://192.168.1.81:61716");
13         Connection connection =  cf.createConnection();
14         connection.start();
15         
16         Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
17         Destination destination = session.createQueue("my-queue");
18         MessageConsumer consumer = session.createConsumer(destination);
19         int i = 0;
20         while(i < 10){
21             Thread.sleep(3000);
22             i++;
23             TextMessage message = (TextMessage)consumer.receive();
24             session.commit();
25             System.out.println("222接收到的消息是:"+message.getText());
26         }
27         session.close();
28         connection.close();
29     }
30 }