ActiveMQ中BrokerService的用例以及如何正确使用它

Question

我是ActiveMQ的新手。我想研究一下它是如何工作通过检查Apache的这个链接提供的示例代码： -

http://activemq.apache.org/how-should-i-implement-request-response-with-jms.html

public class Server implements MessageListener { 
     private static int ackMode; 
     private static String messageQueueName; 
     private static String messageBrokerUrl; 

     private Session session; 
     private boolean transacted = false; 
     private MessageProducer replyProducer; 
     private MessageProtocol messageProtocol; 

     static { 
      messageBrokerUrl = "tcp://localhost:61616"; 
      messageQueueName = "client.messages"; 
      ackMode = Session.AUTO_ACKNOWLEDGE; 
     } 

     public Server() { 
      try { 
       //This message broker is embedded 
       BrokerService broker = new BrokerService(); 
       broker.setPersistent(false); 
       broker.setUseJmx(false); 
       broker.addConnector(messageBrokerUrl); 
       broker.start(); 
      } catch (Exception e) { 
       System.out.println("Exception: "+e.getMessage()); 
       //Handle the exception appropriately 
      } 

      //Delegating the handling of messages to another class, instantiate it before setting up JMS so it 
      //is ready to handle messages 
      this.messageProtocol = new MessageProtocol(); 
      this.setupMessageQueueConsumer(); 
     } 

     private void setupMessageQueueConsumer() { 
      ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(messageBrokerUrl); 
      Connection connection; 
      try { 
       connection = connectionFactory.createConnection(); 
       connection.start(); 
       this.session = connection.createSession(this.transacted, ackMode); 
       Destination adminQueue = this.session.createQueue(messageQueueName); 

       //Setup a message producer to respond to messages from clients, we will get the destination 
       //to send to from the JMSReplyTo header field from a Message 
       this.replyProducer = this.session.createProducer(null); 
       this.replyProducer.setDeliveryMode(DeliveryMode.NON_PERSISTENT); 

       //Set up a consumer to consume messages off of the admin queue 
       MessageConsumer consumer = this.session.createConsumer(adminQueue); 
       consumer.setMessageListener(this); 
      } catch (JMSException e) { 
       System.out.println("Exception: "+e.getMessage()); 
      } 
     } 

     public void onMessage(Message message) { 
      try { 
       TextMessage response = this.session.createTextMessage(); 
       if (message instanceof TextMessage) { 
        TextMessage txtMsg = (TextMessage) message; 
        String messageText = txtMsg.getText(); 
        response.setText(this.messageProtocol.handleProtocolMessage(messageText)); 
       } 

       //Set the correlation ID from the received message to be the correlation id of the response message 
       //this lets the client identify which message this is a response to if it has more than 
       //one outstanding message to the server 
       response.setJMSCorrelationID(message.getJMSCorrelationID()); 

       //Send the response to the Destination specified by the JMSReplyTo field of the received message, 
       //this is presumably a temporary queue created by the client 
       this.replyProducer.send(message.getJMSReplyTo(), response); 
      } catch (JMSException e) { 
       System.out.println("Exception: "+e.getMessage()); 
      } 
     } 

     public static void main(String[] args) { 
      new Server(); 
     } 
    } 

我对messageBrokerUrl =“TCP困惑：//本地主机：61616 “;您知道默认情况下，ActiveMQ服务在端口61616上运行。为什么这个例子选择相同的端口。如果我尝试运行代码thows eception为： 异常：无法绑定到服务器套接字：tcp：// localhost：61616由于：java.net.BindException：地址已在使用中：JVM_Bind

也许如果我更改端口号，我可以执行代码。

请让我知道为什么它是这样的例子以及如何使用BrokerService。

Answer 1

本示例中的BrokerService正在尝试创建一个用于此示例的内存ActiveMQ代理。鉴于你看到的错误，我猜你已经有一台运行在绑定到端口61616的计算机上的ActiveMQ代理，因为这是默认端口，因此两者相冲突。您可以停止外部代理并运行示例，也可以修改示例以不运行嵌入式代理，并仅依赖外部代理实例。

嵌入式代理非常适合单元测试或创建不需要用户安装和运行代理的示例。