主题模式

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  • Topic(主题模式)

    • Topic exchange

      direct类型的Exchange路由规则是完全匹配binding key与routing key,但这种严格的匹配方式在很多情况下不能满足实际业务需求。topic类型的Exchange在匹配规则上进行了扩展,它与direct类型的Exchage相似,也是将消息路由到binding key与routing key相匹配的Queue中,但匹配规则有些不同
      routing_key-它必须是单词列表,以点分隔。这些词可以是任何东西,但是通常它们指定与消息相关的某些功能。一些有效的rounting key 如:"stock.usd.nyse","nyse.vmw","quick.orange.rabbit"。rounting key中可以包含任意多个单词,最多255个字节。
      binding key可以存在如下两种特殊的字符 即:
      1、*(星号)可以代替一个单词。
      2、#(哈希)可以替代零个或多个单词

      ? 在上面图片中,Routing key 设置为"quick.orange.rabbit"的消息将传递到两个队列。消息"lazy.orange.elephant"也将发送给他们两个。但,"quick.orange.fox"只会进入第一个队列,而"lazy.brown.fox"只会进入第二个队列。"lazy.pink.rabbit"将被传递到第二队只有一次,即使两个绑定匹配。"quick.brown.fox"与任何绑定都不匹配,因此将被丢弃。
      如果我们发送一个或四个单词的消息,例如"orange"或"quick.orange.male.rabbit",这些消息将不匹配任何绑定,并且将会丢失。但"lazy.orange.male.rabbit"即使有四个单词,也将匹配最后一个绑定,并将其传送到第二个队列。

    • 生产者消费者代码:

      ? 生产者

      public class TopicEmitLog {
          private static final String EXCHANGE_NAME = "topic_logs";
      
          public static void main(String[] args) throws Exception {
              //获取连接
              Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");
      
              Channel channel = connection.createChannel();
      
              //创建队列
              //channel.queueDeclare("direct_loge",true,false,false,null);
              //声明交换机,
              channel.exchangeDeclare(EXCHANGE_NAME, "topic");
      
              String message="hello";
              //发送消息
      
              //发送消息
              channel.basicPublish(EXCHANGE_NAME, "topics.log", null, message.getBytes("utf-8"));
      
              channel.close();
              connection.close();
      
          }
      
      }

      消费者1可以收到消息

      public class TopicRecv {
      
          public static final String QUEUE_NAME = "topic_queues";
      
          public static final String EXCHANGE_NAME = "topic_logs";
      
          public static void main(String[] args) throws Exception{
              //获取连接
              Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");
      
              //声明通道
              Channel channel = connection.createChannel();
      
              channel.exchangeDeclare(EXCHANGE_NAME, "topic");
              //声明队列队列
              channel.queueDeclare(QUEUE_NAME,false,false,false,null);
              //4.绑定队列到交换器,指定路由key为topics
              channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topics.#");
      
              //
              //channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topic.*");
      
              DeliverCallback deliverCallback = new DeliverCallback(){
                  @Override
                  public void handle(String consumerTag, Delivery delivery) throws IOException {
                      String message = new String(delivery.getBody(), "UTF-8");
                      System.out.println(" [x] Received '" + message + "'");
                  }
              };
      
              channel.basicConsume(QUEUE_NAME, true, deliverCallback, new CancelCallback(){
                  @Override
                  public void handle(String consumerTag) throws IOException {
      
                  }
              });
      
          }
      
      }

      消费者2收不到消息

      public class TopicRecv2 {
      
          public static final String QUEUE_NAME = "topic_queues2";
      
          public static final String EXCHANGE_NAME = "topic_logs";
      
          public static void main(String[] args) throws Exception{
              //获取连接
              Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");
      
              //声明通道
              Channel channel = connection.createChannel();
      
              channel.exchangeDeclare(EXCHANGE_NAME, "topic");
              //声明队列队列
              channel.queueDeclare(QUEUE_NAME,false,false,false,null);
              //4.绑定队列到交换器,指定路由key为topics
              //channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topics.#");
      
              //
              channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topic.*");
      
              DeliverCallback deliverCallback = new DeliverCallback(){
                  @Override
                  public void handle(String consumerTag, Delivery delivery) throws IOException {
                      String message = new String(delivery.getBody(), "UTF-8");
                      System.out.println(" [x] Received '" + message + "'");
                  }
              };
      
              channel.basicConsume(QUEUE_NAME, true, deliverCallback, new CancelCallback(){
                  @Override
                  public void handle(String consumerTag) throws IOException {
      
                  }
              });
      
          }
      
      }

相关代码链接: https://github.com/albert-liu435/springmq

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