Topic类型的Exchange与Direct相比，都是可以根据RoutingKey把消息路由到不同的队列。只不过Topic类型Exchange可以让队列在绑定Routing key 的时候使用通配符！

Routingkey 一般都是有一个或多个单词组成，多个单词之间以”.”分割，例如： snow.com

通配符规则：

#：匹配一个或多个词

*：匹配不多不少恰好1个词

举例：

snow.#：能够匹配snow.com.cn 或者 snow.com

snow.*：只能匹配snow.com

如下图:

解释：

• Queue1：绑定的是china.# ，因此凡是以 china.开头的routing key 都会被匹配到。包括china.news和china.weather
• Queue2：绑定的是#.news ，因此凡是以 .news结尾的 routing key 都会被匹配。包括china.news和japan.news

案例需求：
实现思路如下：

1. 并利用 @RabbitListener 声明 Exchange、Queue、RoutingKey
2. 在 consumer 服务中，编写两个消费者方法，分别监听 business.test.topic.queue1 和business.test.topic.queue2
3. 在 publisher 中编写测试方法，向business.test.topic发送消息

pom

    <dependencies>
        <!--RabbitMQ 依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

yml

server:
  port: 8080
spring:
  rabbitmq:
    host: **.***.**.***
    port: 5672
    username: ****
    password: ****

生产者

import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author: Snow
 * @date: 2023/1/6
 * **************************************************
 * 修改记录(时间--修改人--修改说明):
 */
@RestController
@RequestMapping("/topic")
public class SendController {

    @Autowired
    private RabbitTemplate rabbitTemplate;

    @GetMapping("/send/{message}")
    public void send(@PathVariable("message") String message){
        // 交换机名称
        String exchangeName = "business.test.topic";
        // 发送消息
        if(message.contains("china") && message.contains("news")){
            rabbitTemplate.convertAndSend(exchangeName, "china.news", message);
            return;
        }
        if(message.contains("china")){
            rabbitTemplate.convertAndSend(exchangeName, "china.lala", message);
            return;
        }
        if(message.contains("news")){
            rabbitTemplate.convertAndSend(exchangeName, "lalla.news", message);
            return;
        }

    }


}

消费者

import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;

/**
 * @author: Snow
 * @date: 2023/1/6
 * **************************************************
 * 修改记录(时间--修改人--修改说明):
 */
@Component
public class Consumer {

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "business.test.topic.queue1"),
            exchange = @Exchange(name = "business.test.topic", type = ExchangeTypes.TOPIC),
            key = "china.#"
    ))
    public void listenTopicQueue1(String msg){
        System.out.println("消费者接收到topic.queue1的消息：【" + msg + "】");
    }

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "business.test.topic.queue2"),
            exchange = @Exchange(name = "business.test.topic", type = ExchangeTypes.TOPIC),
            key = "#.news"
    ))
    public void listenTopicQueue2(String msg){
        System.out.println("消费者接收到topic.queue2的消息：【" + msg + "】");
    }
}