SpringBoot的RabbitMQ消息队列: 六、第五模式"Topics"

Topics模式，官方的解释是Receiving messages based on a pattern (topics)，它的结构是

消费者各自监控自己的队列；交换机通过一种模式策略确定生产者的消息放入那个队列。

配置文件。增加类TopicRabbitConfig，编制代码为

 package com.example;

 import org.springframework.amqp.core.Binding;
 import org.springframework.amqp.core.BindingBuilder;
 import org.springframework.amqp.core.Queue;
 import org.springframework.amqp.core.TopicExchange;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 @Configuration
 public class TopicRabbitConfig {

     final static String message = "topic.message";
     final static String messages = "topic.messages";

     @Bean
     public Queue queueMessage() {
         return new Queue(TopicRabbitConfig.message);
     }

     @Bean
     public Queue queueMessages() {
         return new Queue(TopicRabbitConfig.messages);
     }

     @Bean
     TopicExchange exchange() {
         return new TopicExchange("exchange");
     }

     @Bean
     Binding bindingExchangeMessage(Queue queueMessage, TopicExchange exchange) {
         return BindingBuilder.bind(queueMessage).to(exchange).with("topic.message");
     }

     @Bean
     Binding bindingExchangeMessages(Queue queueMessages, TopicExchange exchange) {
         return BindingBuilder.bind(queueMessages).to(exchange).with("topic.#");
     }
 }

7、消息发送。增加类TopicSender，编制代码为

 package com.example;

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.amqp.core.AmqpTemplate;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;

 @Component
 public class TopicSender {


     protected static Logger logger=LoggerFactory.getLogger(TopicSender.class);

     @Autowired
     private AmqpTemplate rabbitTemplate;
     public void send1() {
         String context = "hi, i am message 1";
         logger.debug("Sender : " + context);
         this.rabbitTemplate.convertAndSend("exchange", "topic.message", context);
     }

     public void send2() {
         String context = "hi, i am messages 2";
         logger.debug("Sender : " + context);
         this.rabbitTemplate.convertAndSend("exchange", "topic.messages", context);
     }
 }

8、消息接收1.增加类TopicReceiver，编制代码为

 package com.example;

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.amqp.rabbit.annotation.RabbitHandler;
 import org.springframework.amqp.rabbit.annotation.RabbitListener;
 import org.springframework.stereotype.Component;

 @Component
 @RabbitListener(queues = "topic.message")
 public class TopicReceiver {

     protected static Logger logger=LoggerFactory.getLogger(TopicReceiver.class);

     @RabbitHandler
     public void process(String message) {
         logger.debug("Topic Receiver1  : " + message);
     }

 }

9、消息接收2.增加类TopicReceiver2，编制代码为

 package com.example;

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.amqp.rabbit.annotation.RabbitHandler;
 import org.springframework.amqp.rabbit.annotation.RabbitListener;
 import org.springframework.stereotype.Component;

 @Component
 @RabbitListener(queues = "topic.messages")
 public class TopicReceiver2 {

     protected static Logger logger=LoggerFactory.getLogger(TopicReceiver2.class);


     @RabbitHandler
     public void process(String message) {
         logger.debug("Topic Receiver2  : " + message);
     }

 }

10、RestController。增加类TopicController，编制代码为

 package com.example;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;

 @RestController
 public class TopicController {

     @Autowired
     private TopicSender topicSender;

     @RequestMapping("/send1")
     public String send1() {
         topicSender.send1();
         return "send1 ok";
     }

     @RequestMapping("/send2")
     public String send2() {
         topicSender.send2();
         return "send2 ok";
     }
 }

11、运行工程。在工程所在文件夹打开cmd,输入mvn spring-boot:run

12、在浏览器中分别输入http://localhost:9080/send1 ,http://localhost:9080/send2,查看控制台输出
http://localhost:9080/send1,控制台的输出，两个接收器都收到消息

http://localhost:9080/send2,控制台的输出，第二个接收器收到消息

13、小结

A、在配置文件中，定义了一个TopicExchange,然后对两个队列，分别配置了绑定规则。（变更绑定规则测试时，先停止命令行的spring-boot，再删除rabbitmq management中的队列）。

B、发送器，发送send1会匹配到topic.#和topic.message 两个Receiver都可以收到消息，发送send2只有topic.#可以匹配所有只有Receiver2监听到消息。

     发送器在发送消息时，使用的方法是需要传入一个特定的交换机的。

C、接收器，依然各自监控自己的队列；