SpringBoot整合RabbitMQ系列（三）延迟消费

前言

在实际工作中，我们往往要实现一些延迟通知的功能，比如订单未付款30分钟后自动取消、邮件半小时后发送等等。
通过RabbitMq实现延迟队列主要有两种方式：

1. 添加rabbitmq_delayed_message_exchange插件
2. 通过死信队列机制
   本篇用的是第二种。

实现步骤

1. 创建一条死信队列
2. 创建一条没有消费者消费的队列，用于消息超时后发送到死信队列
3. 定时发送消息，观察是否成功延迟消费

代码演示

package org.jz.rabbitmq.chapter3;

import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.QueueBuilder;
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.context.annotation.Bean;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;

@Slf4j
@EnableScheduling
@SpringBootApplication
public class Chapter3Application {


    @Autowired
    RabbitTemplate rabbitTemplate;

    public static void main(String[] args) {
        SpringApplication.run(Chapter3Application.class, args);
    }

    @Bean
    public org.springframework.amqp.core.Queue queue() {
        org.springframework.amqp.core.Queue queue = QueueBuilder.durable("delay")
                .withArgument("x-dead-letter-exchange", "dead.direct") 
                .withArgument("x-dead-letter-routing-key", "dead")    
                .withArgument("x-message-ttl", 5000)    //设置消息存活时间为5s
                .build();
        return queue;
    }

    //创建并且监听一条死信队列
    @RabbitListener(bindings = @QueueBinding(value = @Queue(value = "dead"),
            exchange = @Exchange(name = "dead.direct"), key = "dead"))
    public void listenDead(String str) {
        log.info("延时五秒接收到的消息: {}", str);
    }

    //延时5秒防止queue没有初始化成功
    @Scheduled(initialDelay = 6000, fixedRate = 6000)
    public void sendDelay() {
        log.info("发送一条消息");
        rabbitTemplate.convertAndSend("delay", "hello");
    }
}

结果输出

2019-11-16 07:51:13.421  INFO 41664 --- [   scheduling-1] o.j.r.chapter3.Chapter3Application       : 发送一条消息
2019-11-16 07:51:18.483  INFO 41664 --- [ntContainer#0-1] o.j.r.chapter3.Chapter3Application       : 延时五秒接收到的消息: hello
2019-11-16 07:51:19.421  INFO 41664 --- [   scheduling-1] o.j.r.chapter3.Chapter3Application       : 发送一条消息
2019-11-16 07:51:24.453  INFO 41664 --- [ntContainer#0-1] o.j.r.chapter3.Chapter3Application       : 延时五秒接收到的消息: hello