RabbitMQ的Exchange 模式之Fanout（广播模式）

你的名字 2022-06-04 01:59 247阅读 0赞

该模式示意图：  
  
![这里写图片描述][SouthEast]  
  
![这里写图片描述][SouthEast 1]  
![这里写图片描述][SouthEast 2]

服务端以fanout模式发布消息，服务端并不需要指定队列名，只需要指定特定的exchange，客户端也只需要创建一个随机队列，使该队列与exchange关联(binding)就可以接收到服务端发布的消息，这样做的好处就是同一个exchange发布的消息，不同的客户端可以进不同的处理，实现了发送方代码和消费者的代码完全解耦合  
  
服务端java实现

package com.adtec.rabbitmq;
    import com.rabbitmq.client.BuiltinExchangeType;
    import com.rabbitmq.client.ConnectionFactory;
    import com.rabbitmq.client.Connection;
    import com.rabbitmq.client.Channel;
    
    public class EmitLog {
    
      private static final String EXCHANGE_NAME = "logs";
    
      public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        //EXCHANGE模式为BuiltinExchangeType.FANOUT
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);
    
        String message = "info: Hello World!";
    
        channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes("UTF-8"));
        System.out.println(" [x] Sent '" + message + "'");
    
        channel.close();
        connection.close();
      }
    }

客户端java实现：

package rabbitmq;
    
    import com.rabbitmq.client.*;
    
    import java.io.IOException;
    
    public class ReceiveLogs { 
      private static final String EXCHANGE_NAME = "logs";
    
      public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        //创建一个名为logs的fanout类型的Exchange
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);
        //获取一个随机队列名
        String queueName = channel.queueDeclare().getQueue();
        //队列和Exchange进行binding
        channel.queueBind(queueName, EXCHANGE_NAME, "");
    
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
        // 监听消息
        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 '" + message + "'");
          }
        };
        channel.basicConsume(queueName, true, consumer);
      }
    }

运行时先启动客户端，在启动服务端。

[SouthEast]: /images/20220604/e58d973d6328435ea07f6afea96b04e5.png
[SouthEast 1]: /images/20220604/d26beeba66e445878d969e64364fb3ca.png
[SouthEast 2]: /images/20220604/d50cdbb5d6144e7e9957bd33a825f9fe.png