RabbitMQ 六种基本队列模式 ----- 消息订阅(Publish/Subscribe)

我们将向多个消费者传递一条信息。这种模式称为“发布/订阅”

**在之前的文章 P 和 C 已经很清楚是什么意思了，这里面的X代表的是交换机（Exchange）。交换机只负责转发消息，不具有存储消息的能力，因此如果没有队列与交换机绑定，或者没有符合规则的队列，那么消息就会丢失**

交换机的类型

• Fanout: 广播，发送到每个与交换机绑定的队列
• Direct: 定向
• Topic: 通配符
• Headers: 参数匹配

使用 java 来实现简单的 Publish/Subscribe

• 导入 Maven 坐标

  <!-- https://mvnrepository.com/artifact/com.rabbitmq/amqp-client -->
  <dependency>
      <groupId>com.rabbitmq</groupId>
      <artifactId>amqp-client</artifactId>
      <version>5.9.0</version>
  </dependency>
  
  <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-simple -->
  <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-simple</artifactId>
      <version>1.7.25</version>
  <!--            <scope>test</scope>-->
  </dependency>
  

• 编写 Publish 端代码

  public static void main(String[] args) {
          final String EXCHANGE_NAME = "logs";
          try {
              ConnectionFactory factory = new ConnectionFactory();
              // 设置参数
              factory.setHost("192.168.3.64");
              factory.setPort(5672);
              factory.setVirtualHost("/default_virtual_host");
              factory.setUsername("admin");
              factory.setPassword("admin");
  
              Connection connection = factory.newConnection();
              Channel channel = connection.createChannel();
              // 创建交换机
              channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT, true, false, false, null);
              // 创建队列
              channel.queueDeclare("log_fanout_queue1", false, false, false, null);
              channel.queueDeclare("log_fanout_queue2", false, false, false, null);
              // 绑定队列
              channel.queueBind("log_fanout_queue1", EXCHANGE_NAME, "");
              channel.queueBind("log_fanout_queue2", EXCHANGE_NAME, "");
              // 发送消息
              String message = "[日志][支付信息][订单号:" + new Date().getTime() +"][支付ID:10]";
              channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes(StandardCharsets.UTF_8));
              // 释放资源
              channel.close();
              connection.close();
  
          } catch (IOException | TimeoutException e) {
              e.fillInStackTrace();
          }
      }
  

• 编写第一个 Subscribe 端代码

  public static void main(String[] args) {
          final String EXCHANGE_NAME = "logs";
  
          try {
              ConnectionFactory factory = new ConnectionFactory();
              // 设置参数
              factory.setHost("192.168.3.64");
              factory.setPort(5672);
              factory.setVirtualHost("/default_virtual_host");
              factory.setUsername("admin");
              factory.setPassword("admin");
  
              Connection connection = factory.newConnection();
              Channel channel = connection.createChannel();
  
              channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT, true, false, false, null);
  
              String queue1Name = "log_fanout_queue1";
  
  //            channel.queueBind(queue1Name, EXCHANGE_NAME, "");
  
              DeliverCallback deliverCallback = (consumerTag, delivery) -> {
                  String message = new String(delivery.getBody(), StandardCharsets.UTF_8);
                  System.out.println(" [x] Received '" + message + "'");
              };
              channel.basicConsume(queue1Name, true, deliverCallback, consumerTag -> {
              });
  
          } catch (IOException e) {
              e.printStackTrace();
          } catch (TimeoutException e) {
              e.printStackTrace();
          }
      }
  

• 编写第二个 Subscribe 端代码

  
  public static void main(String[] args) {
          final String EXCHANGE_NAME = "logs";
  
          try {
              ConnectionFactory factory = new ConnectionFactory();
              // 设置参数
              factory.setHost("192.168.3.64");
              factory.setPort(5672);
              factory.setVirtualHost("/default_virtual_host");
              factory.setUsername("admin");
              factory.setPassword("admin");
  
              Connection connection = factory.newConnection();
              Channel channel = connection.createChannel();
  
              channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT, true, false, false, null);
  
              String queue2Name = "log_fanout_queue2";
  
  //            channel.queueBind(queue2Name, EXCHANGE_NAME, "");
  
              DeliverCallback deliverCallback = (consumerTag, delivery) -> {
                  String message = new String(delivery.getBody(), StandardCharsets.UTF_8);
                  System.out.println(" [x] Received '" + message + "'");
              };
              channel.basicConsume(queue2Name, true, deliverCallback, consumerTag -> {
              });
  
          } catch (IOException e) {
              e.printStackTrace();
          } catch (TimeoutException e) {
              e.printStackTrace();
          }
      }
  

• 启动消费者和生产者

  • 消息队列展示

    

  • 消费者接收到的消息