rabbitMq实现延时队列

    rabbitMq是受欢迎的消息中间件之一，相比其余的消息中间件，具备高并发的特性（天生具有高并发高可用的erlang语言编写），除此以外，还能够持久化，保证消息不易丢失，高可用，实现集群部署，提供灵活的路由和可靠性，可视化管理等等的优势。

    相比于其余的消息队列，rabbitmq最大的特点就是加入了exchange（交换器）这个东西，AMQP协议中的核心思想就是生产者和消费者隔离，生产者从不直接将消息发送给队列。生产者一般不知道是否一个消息会被发送到队列中，只是将消息发送到一个交换机。先由Exchange来接收，而后Exchange按照特定的策略转发到Queue进行存储。同理，消费者也是如此。Exchange 就相似于一个交换机，转发各个消息分发到相应的队列中。

      RabbitMQ经常使用的Exchange Type有三种：fanout、direct、topic。

      fanout:把全部发送到该Exchange的消息投递到全部与它绑定的队列中。

      direct:把消息投递到那些binding key与routing key彻底匹配的队列中。

      topic:将消息路由到binding key与routing key模式匹配的队列中。

言归正传，延时队列如何经过rabbitmq来实现呢？

分析：首先rabbitmq本身是不具有延时的功能的，除了使用官方提供的插件以外，咱们还能够经过ttl（设置超时时间的方式）+ DLX（一个死信队列）的方式来实现 + Router（转发队列）

其中，ttl能够设置在消息上，也能够设置在队列上，设置在消息上能够提供更大的灵活性，可是若是同时设置超时时间的话，就取最小的超时时间为准。

此外，死信队列是一个普通的队列，它没有消费者，用来存储有超时时间信息的消息，而且能够设置当消息超时（ttl），转发到另外一个指定队列(此处设置转发到router, 当发送消息以后（发送时，带上要延时的队列名称），等待消息超时，将消息转发到指定的Router队列。

最后，转发队列，用来接收死信队列超时消息，在接收到以后，消费者将消息解析，获取queueName，body,再向所获取的queueName队列发送一条消息，内容为body.

下面是代码：

生产者：

package cn.chinotan.service.delayQueueRabbitMQ;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.amqp.AmqpException;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessagePostProcessor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @program: test
 * @description: 生产者
 * @author: xingcheng
 * @create: 2018-08-12 12:33
 **/
@Service
public class Producr {
    private static final Logger LOGGER = LoggerFactory.getLogger(Producr.class);

    @Autowired
    private AmqpTemplate amqpTemplate;

    public void send(String msg, long time, String delayQueueName) {
        //rabbit默认为毫秒级
        long times = time * 1000;
        MessagePostProcessor processor = new MessagePostProcessor() {

            @Override
            public Message postProcessMessage(Message message) throws AmqpException {
                message.getMessageProperties().setExpiration(String.valueOf(times));
                return message;
            }
        };
        // 拼装msg
        msg = StringUtils.join(msg, ":", delayQueueName);
        amqpTemplate.convertAndSend(MqConstant.MY_EXCHANGE, MqConstant.DEAD_LETTER_QUEUE, msg, processor);
    }
}

消费队列1：

package cn.chinotan.service.delayQueueRabbitMQ;

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.Service;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @program: test
 * @description: queueOne消费者
 * @author: xingcheng
 * @create: 2018-08-12 12:35
 **/
@Service
public class MyQueueOneConsumer {
    private static final Logger LOGGER = LoggerFactory.getLogger(MyQueueOneConsumer.class);

    @RabbitListener(queues=MqConstant.MY_QUEUE_ONE)
    @RabbitHandler
    public void process(String content) {
        LOGGER.info("延迟时间到，queueOne开始执行 {}", new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
    }
}

消费队列2：

package cn.chinotan.service.delayQueueRabbitMQ;

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.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @program: test
 * @description: queueTwo队列
 * @author: xingcheng
 * @create: 2018-08-12 12:35
 **/
@Service
public class MyQueueTwoConsumer {
    private static final Logger LOGGER = LoggerFactory.getLogger(MyQueueTwoConsumer.class);
    @Autowired
    private Producr producr;

    @RabbitListener(queues=MqConstant.MY_QUEUE_TWO)
    @RabbitHandler
    public void process(String content) {
        LOGGER.info("延迟时间到，queueTwo开始执行 {}", new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
    }
}

转发队列：

package cn.chinotan.service.delayQueueRabbitMQ;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.amqp.rabbit.annotation.RabbitHandler;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @program: test
 * @description: 转发队列
 * @author: xingcheng
 * @create: 2018-08-12 12:35
 **/
@Service
public class TradeProcess {
    private static final Logger LOGGER = LoggerFactory.getLogger(TradeProcess.class);

    @Autowired
    private AmqpTemplate amqpTemplate;
    
    @RabbitListener(queues=MqConstant.MY_TRANS_QUEUE)
    @RabbitHandler
    public void process(String content) {
        String msg = content.split(":")[0];
        String delayQueueName = content.split(":")[1];
        amqpTemplate.convertAndSend(MqConstant.MY_EXCHANGE, delayQueueName, msg);
        LOGGER.info("进行转发 {}", new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
    }
}

队列配置：

package cn.chinotan.service.delayQueueRabbitMQ;

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

import java.util.HashMap;
import java.util.Map;

/**
 * @program: test
 * @description: 延时队列rabbitMQ配置
 * @author: xingcheng
 * @create: 2018-08-12 12:27
 **/
@Configuration
public class RabbitConfig {

    @Bean
    public DirectExchange myExchange() {
        return new DirectExchange(MqConstant.MY_EXCHANGE, true, false);
    }

    @Bean
    public Queue myQueueOne() {
        return new Queue(MqConstant.MY_QUEUE_ONE, true, false, false);
    }

    @Bean
    public Queue myQueueTwo() {
        return new Queue(MqConstant.MY_QUEUE_TWO, true, false, false);
    }
    @Bean
    public Queue myTransQueue() {
        return new Queue(MqConstant.MY_TRANS_QUEUE, true, false, false);
    }

    @Bean
    public Queue deadLetterQueue() {
        Map<String, Object> map = new HashMap<>();
        map.put("x-dead-letter-exchange", MqConstant.MY_EXCHANGE);
        map.put("x-dead-letter-routing-key", MqConstant.MY_TRANS_QUEUE);
        Queue queue = new Queue(MqConstant.DEAD_LETTER_QUEUE, true, false, false, map);
        System.out.println("arguments :" + queue.getArguments());
        return queue;
    }

    @Bean
    public Binding queueOneBinding() {
        return BindingBuilder.bind(myQueueOne()).to(myExchange()).with(MqConstant.MY_QUEUE_ONE);
    }

    @Bean
    public Binding queueTwoBinding() {
        return BindingBuilder.bind(myQueueTwo()).to(myExchange()).with(MqConstant.MY_QUEUE_TWO);
    }

    @Bean
    public Binding queueDeadBinding() {
        return BindingBuilder.bind(deadLetterQueue()).to(myExchange()).with(MqConstant.DEAD_LETTER_QUEUE);
    }

    @Bean
    public Binding queueTransBinding() {
        return BindingBuilder.bind(myTransQueue()).to(myExchange()).with(MqConstant.MY_TRANS_QUEUE);
    }
}

队列常量配置：

package cn.chinotan.service.delayQueueRabbitMQ;

/**
 * @program: test
 * @description: rabbitMq常量
 * @author: xingcheng
 * @create: 2018-08-12 12:30
 **/
public class MqConstant {
    
    public static final String MY_EXCHANGE = "my_exchange";
    
    public static final String MY_QUEUE_ONE = "my_queue_one";

    public static final String MY_QUEUE_TWO = "my_queue_two";
    
    public static final String DEAD_LETTER_QUEUE = "dead_letter_queue";
    
    public static final String MY_TRANS_QUEUE = "my_trans_queue";
    
}

测试延时controller：

package cn.chinotan.controller;

import cn.chinotan.service.delayQueueRabbitMQ.MqConstant;
import cn.chinotan.service.delayQueueRabbitMQ.Producr;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @program: test
 * @description: 延时队列启动类
 * @author: xingcheng
 * @create: 2018-08-12 15:41
 **/
@RestController
@RequestMapping("/delayQueue")
public class DelayQueueController {

    private static final Logger LOGGER = LoggerFactory.getLogger(DelayQueueController.class);

    @Autowired
    private Producr producr;

    @GetMapping("/send/{time}")
    public String send(@PathVariable("time") int time){
        LOGGER.info("{}秒后, 发送延迟消息，当前时间{}", time, new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
        producr.send("我是延时消息...", time, MqConstant.MY_QUEUE_TWO);
        return "ok";
    }
    
}

测试结果：