RabbitMQ的Exchange 模式之direct（指定模式）

小咪咪 2022-06-04 01:19 245阅读 0赞

direct模式是rabbitmq的默认模式，看懂了下图基本就明白了该模式  
![这里写图片描述][direct-exchange.png]  
在这个模式中，我们可以看到两个队列在direct模式下绑定的Exchange（交换机）X. 第一个队列用binding key（绑定关键字）orange绑定，第二个队列有两个binding key，一个为black，一个是green

在这种模式中，通过binding key orange发布到Exchange的消息 将被路由到Q1队列。带有black 或green的路由键的消息将进入Q2。所有其他消息将被丢弃。

客户端方面，可以binding一个或多个路由键，用以接收自己“感兴趣”的消息

例如：服务端可能推送了”info”,”warning”,”error”等消息，而客户端只对”warning”,”error”感兴趣

服务端代码：

package com.adtec.rabbitmq;
    
    import com.rabbitmq.client.*;
    
    
    public class EmitLogDirect { 
    
        private static final String EXCHANGE_NAME = "direct_logs";
    
        public static void main(String[] argv)
                      throws java.io.IOException, Exception {
    
            ConnectionFactory factory = new ConnectionFactory();
            factory.setHost("localhost");
            Connection connection = factory.newConnection();
            Channel channel = connection.createChannel();
    
            channel.exchangeDeclare(EXCHANGE_NAME, "direct");
            String[] severitys = {
       "info","warning","error"};
    
            String message = "message from";
            //一次发布"info","warning","error"消息
            for(String severity: severitys){
                String msg = message + severity;
                channel.basicPublish(EXCHANGE_NAME, severity, null, msg.getBytes());
                System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
            }
            channel.close();
            connection.close();
        }
        //..
    }

客户端代码：

package rabbitmq;
    
    import com.rabbitmq.client.*;
    
    import java.io.IOException;
    
    public class ReceiveLogsDirect { 
    
        private static final String EXCHANGE_NAME = "direct_logs";
    
        public static void main(String[] argv) throws Exception {
            ConnectionFactory factory = new ConnectionFactory();
            factory.setHost("localhost");
            Connection connection = factory.newConnection();
            Channel channel = connection.createChannel();
    
            channel.exchangeDeclare(EXCHANGE_NAME, "direct");
            String queueName = channel.queueDeclare().getQueue();
    
            System.err.println("Usage: ReceiveLogsDirect [info] [warning] [error]");
    
            // 只关心error和warning
            String[] severitys = { "error", "warning" };
    
            for (String severity : severitys) {
                channel.queueBind(queueName, EXCHANGE_NAME, severity);
            }
            System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
    
            Consumer consumer = new DefaultConsumer(channel) {
                @Override
                public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
                        byte[] body) throws IOException {
                    String message = new String(body, "UTF-8");
                    System.out.println(" [x] Received '" + envelope.getRoutingKey() + "':'" + message + "'");
                }
            };
            channel.basicConsume(queueName, true, consumer);
        }
    }

先运行客户端，在执行服务端  
  
服务端执行结果  
  
![这里写图片描述][SouthEast]  
  
客户端执行接收的消息  
  
![这里写图片描述][SouthEast 1]

[direct-exchange.png]: http://www.rabbitmq.com/img/tutorials/direct-exchange.png
[SouthEast]: /images/20220604/ff34b0a0d02b444b9380ef314a602086.png
[SouthEast 1]: /images/20220604/e641a7ce81324005a7c994ddc5ca7796.png