Exchange是什么
我们可以将 Exchange 当做一个消息的中转站，所有的消息在发送到指定队列前都要经过这一层中转站。中转站再根据某些规则进行匹配来决定将消息分发到哪些队列中。
Exchange的几种类型
- Direct（默认）
只有当 Routing Key 等于 Binding Key 时，消息才会被路由到队列中。 - Fanout
实现了一种广播机制，将消息发送到所有与这个 Exchange 绑定的队列中。 - Topic
定义了一种匹配规则，同样根据 Routing Key 和 Binding Key 进行模糊匹配，更加灵活。 - Headers
Headers Exchange 会忽略 RoutingKey 而根据消息中的 Headers 和创建绑定关系时指定的 Arguments 来匹配决定路由到哪些 Queue，其性能比较差而且 Direct Exchange 完全可以代替它，所以不建议使用。
Exchange 的创建与绑定
@RabbitListener(bindings = @QueueBinding(value = @Queue(value = "队列名"),
exchange = @Exchange(name = "交换机名称"), key = "Binding Key"))
public void listen(String msg) {
log.info("成功消费队列的消息: {}", msg);
}
以上就是一个通过注解声明队列同时绑定Exchange的一个列子。
如果仅声明一条队列，那么当它被创建时，后台会自动将这个队列绑定到一个名称为空的 Direct Exchange 上，绑定 Routing Key 与队列名称相同。
代码示例
package com.jiangzhe.rabbitmq.chapter2;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.core.Message;
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.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
@Slf4j
@EnableScheduling
@SpringBootApplication
public class Chapter2Application {
private static final String FANOUT_EXCHANGE_NAME = "amqp.fanout";
private static final String TOPIC_EXCHANGE_NAME = "amqp.topic";
private static final String DIRECT_EXCHANGE_NAME = "amqp.direct";
@Autowired
private RabbitTemplate rabbitTemplate;
public static void main(String[] args) {
SpringApplication.run(Chapter2Application.class, args);
}
@RabbitListener(bindings = @QueueBinding(value = @Queue(value = "direct"),
exchange = @Exchange(name = DIRECT_EXCHANGE_NAME), key = "direct.cn"))
public void listenDirect(String msg, Message message) {
String consumerQueue = message.getMessageProperties().getConsumerQueue();
log.info("成功消费队列 {} 的消息: {}", consumerQueue, msg);
}
@RabbitListener(bindings = {
@QueueBinding(value = @Queue(value = "fanoutA"),
exchange = @Exchange(type = ExchangeTypes.FANOUT, name = FANOUT_EXCHANGE_NAME)),
@QueueBinding(value = @Queue(value = "fanoutB"),
exchange = @Exchange(type = ExchangeTypes.FANOUT, name = FANOUT_EXCHANGE_NAME)),
@QueueBinding(value = @Queue(value = "fanoutC"),
exchange = @Exchange(type = ExchangeTypes.FANOUT, name = FANOUT_EXCHANGE_NAME))})
public void listenFanout(String msg, Message message) {
String consumerQueue = message.getMessageProperties().getConsumerQueue();
log.info("成功消费队列 {} 的消息: {}", consumerQueue, msg);
}
/**
* 其中*代表匹配任意的一个词，#代表匹配0或多个词
*/
@RabbitListener(bindings = {
@QueueBinding(value = @Queue(name = "topicA"),
exchange = @Exchange(type = ExchangeTypes.TOPIC, name = TOPIC_EXCHANGE_NAME), key = "topic.cn.#"),
@QueueBinding(value = @Queue(name = "topicB"),
exchange = @Exchange(type = ExchangeTypes.TOPIC, name = TOPIC_EXCHANGE_NAME), key = "topic.com.*"),
@QueueBinding(value = @Queue(name = "topicC"),
exchange = @Exchange(type = ExchangeTypes.TOPIC, name = TOPIC_EXCHANGE_NAME), key = "topic.#"),
})
public void listenTopic(String msg, Message message) {
String consumerQueue = message.getMessageProperties().getConsumerQueue();
log.info("成功消费队列 {} 的消息: {}", consumerQueue, msg);
}
@Scheduled(initialDelay = 2000, fixedRate = 1000000)
public void send() throws InterruptedException {
log.info("----------------------------");
log.info("direct");
rabbitTemplate.convertAndSend(DIRECT_EXCHANGE_NAME, "direct.cn", "hello");
Thread.sleep(1000);
log.info("----------------------------");
log.info("fanout");
rabbitTemplate.convertAndSend(FANOUT_EXCHANGE_NAME, "这个值无效", "hello");
Thread.sleep(1000);
log.info("----------------------------");
log.info("to topicC and topicC");
rabbitTemplate.convertAndSend(TOPIC_EXCHANGE_NAME, "topic.com.a", "hello");
Thread.sleep(1000);
log.info("----------------------------");
log.info("to topicA and topicC");
rabbitTemplate.convertAndSend(TOPIC_EXCHANGE_NAME, "topic.cn", "hello");
}
}
输出结果
2019-11-02 12:54:09.775 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : ----------------------------
2019-11-02 12:54:09.775 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : direct
2019-11-02 12:54:09.849 INFO 2756 --- [ntContainer#2-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 direct 的消息: hello
2019-11-02 12:54:10.809 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : ----------------------------
2019-11-02 12:54:10.809 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : fanout
2019-11-02 12:54:10.839 INFO 2756 --- [ntContainer#1-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 fanoutA 的消息: hello
2019-11-02 12:54:10.839 INFO 2756 --- [ntContainer#1-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 fanoutB 的消息: hello
2019-11-02 12:54:10.839 INFO 2756 --- [ntContainer#1-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 fanoutC 的消息: hello
2019-11-02 12:54:11.809 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : ----------------------------
2019-11-02 12:54:11.809 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : to topicC and topicC
2019-11-02 12:54:11.838 INFO 2756 --- [ntContainer#0-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 topicB 的消息: hello
2019-11-02 12:54:11.838 INFO 2756 --- [ntContainer#0-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 topicC 的消息: hello
2019-11-02 12:54:12.810 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : ----------------------------
2019-11-02 12:54:12.810 INFO 2756 --- [ scheduling-1] c.j.r.chapter2.Chapter2Application : to topicA and topicC
2019-11-02 12:54:12.840 INFO 2756 --- [ntContainer#0-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 topicC 的消息: hello
2019-11-02 12:54:12.840 INFO 2756 --- [ntContainer#0-1] c.j.r.chapter2.Chapter2Application : 成功消费队列 topicA 的消息: hello