1.为什么会用到延时队列?

场景: 最近在开发一款系统中遇到这样一个场景,A系统开通套餐需要把套餐信息以邮件的形式发送给相关工作人员,经过人工审核通过后,在B系统里面开通,A系统会调B系统套餐列表接口查询套餐是否开通成功,开通成功则从A系统去完成订单,假如超过设定时间未开通成功,则关闭订单并退费.
(这东西俗称"套娃")
这时候用RabbitMQ的延时队列就可以完美的解决这个问题

2.为什么会提到多策略?

场景: 假如A系统还有别的功能添加需要经过人工审核之后在B系统中添加成功之后,A系统才会显示添加成功,但是又不想写很多队列啊消费者等代码.就可以用到这种策略模式,换句话说就是类似 if… else …能明白了吧.

3.进入今天主题

整体流程图:
在这里插入图片描述

生产者生产一条延时消息，根据需要延时时间的不同，利用routingkey将消息路由到延时队列，队列都设置了TTL属性，并绑定到死信交换机中，消息过期后，根据routingkey又会被路由到死信队列中，消费者只需要监听死信队列,拿到消息去具体的策略实现类进行后续业务处理即可。

有了这个图写代码就简单了.
mq配置类声明队列,路由键,交换机之间的关系;以及生产者消费者 rabbitmq等Bean

RabbitMqConfig

注意监听我也写在配置类里面SimpleMessageListenerContainer用的这个类去设置的队列
simpleMessageListenerContainer.setQueueNames(DEAD_LETTER_QUEUE_NAME);

package com.king.alice.rabbitmq.config;


import com.king.alice.rabbitmq.delay.consumer.MessageConsumer;
import com.king.alice.rabbitmq.delay.consumer.Strategy;
import com.king.alice.rabbitmq.delay.provider.MessageProvider;
import org.springframework.amqp.core.*;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

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

/**
 * @Author wlt
 * @Description rabbitmq配置类
 * @Date 2022/9/4
 * @Param
 * @return
 **/

@Configuration
public class RabbitMqConfig {

    public static final String DELAY_EXCHANGE_NAME = "delay.alice.exchange";
    public static final String DELAY_QUEUE_NAME = "delay.alice.queue";
    public static final String DELAY_QUEUE_ROUTING_KEY = "delay.alice.queue.routing.key";
    public static final String DEAD_LETTER_EXCHANGE = "ttl.alice.exchange";
    public static final String DEAD_LETTER_QUEUE_ROUTING_KEY = "ttl.alice.queue.routing.key";
    public static final String DEAD_LETTER_QUEUE_NAME = "ttl.alice.queue";

    /**
     * 声明延时Exchange
     * @return
     */
    @Bean("delayExchange")
    public DirectExchange delayExchange(){
        return new DirectExchange(DELAY_EXCHANGE_NAME);
    }

    /**
     * 功能描述: <br>
     * <声明死信Exchange>
     */
    @Bean("deadLetterExchange")
    public DirectExchange deadLetterExchange(){
        return new DirectExchange(DEAD_LETTER_EXCHANGE);
    }

    /**
     * 声明延时队列 并绑定到对应的死信交换机
     * @return
     */
    @Bean("delayQueue")
    public Queue delayQueue(){
        Map<String, Object> args = new HashMap<>(2);
        // x-dead-letter-exchange    这里声明当前队列绑定的死信交换机
        args.put("x-dead-letter-exchange", DEAD_LETTER_EXCHANGE);
        // x-dead-letter-routing-key  这里声明当前队列的死信路由key
        args.put("x-dead-letter-routing-key", DEAD_LETTER_QUEUE_ROUTING_KEY);
        // x-message-ttl  声明队列的TTL
//        args.put("x-message-ttl", 6000);
        return QueueBuilder.durable(DELAY_QUEUE_NAME).withArguments(args).build();
    }



    /**
     * 功能描述: <br>
     * <声明死信队列用于接收延时处理的消息>
     */
    @Bean("deadLetterQueue")
    public Queue deadLetterQueue(){
        return new Queue(DEAD_LETTER_QUEUE_NAME);
    }


    /**
     * 功能描述: <br>
     * <声明延时队列绑定关系>
     * @Param:
     * @Return:
     * @Author: 大魔王
     * @Date: 2023/8/15 20:00
     */
    @Bean
    public Binding delayBinding(@Qualifier("delayQueue") Queue queue,
                                 @Qualifier("delayExchange") DirectExchange exchange){
        return BindingBuilder.bind(queue).to(exchange).with(DELAY_QUEUE_ROUTING_KEY);
    }



    /**
     * 功能描述: <br>
     * <声明死信队列A绑定关系>
     * @Param:
     * @Return:
     * @Author: 大魔王
     * @Date: 2023/8/15 20:01
     */
    @Bean
    public Binding deadLetterBinding(@Qualifier("deadLetterQueue") Queue queue,
                                      @Qualifier("deadLetterExchange") DirectExchange exchange){
        return BindingBuilder.bind(queue).to(exchange).with(DEAD_LETTER_QUEUE_ROUTING_KEY);
    }

    @Bean
    @ConditionalOnMissingBean
    public MessageProvider messageProvider(@Qualifier("delayRabbitTemplate") RabbitTemplate template) {
        return new MessageProvider(template);
    }

    @Bean
    @ConditionalOnMissingBean
    public MessageConsumer messageConsumer(ObjectProvider<List<Strategy>> provider) {
        return new MessageConsumer(provider);
    }

    @Bean
    @ConditionalOnMissingBean
    public RabbitTemplate delayRabbitTemplate(ConnectionFactory connectionFactory) {
        RabbitTemplate template = new RabbitTemplate(connectionFactory);
        template.setMessageConverter(new Jackson2JsonMessageConverter());
        return template;
    }

    @Bean
    SimpleMessageListenerContainer simpleMessageListenerContainer(MessageConsumer messageConsumer, ConnectionFactory factory) {
        SimpleMessageListenerContainer simpleMessageListenerContainer = new SimpleMessageListenerContainer(factory);
        simpleMessageListenerContainer.setQueueNames(DEAD_LETTER_QUEUE_NAME);
        simpleMessageListenerContainer.setExposeListenerChannel(true);
        simpleMessageListenerContainer.setMessageListener(messageConsumer);
        return simpleMessageListenerContainer;
    }

    public static final String EXCHANGE_NAME = "alice_topic_exchange";

    public static final String QUEUE_NAME = "alice_queue";

    @Bean("aliceExchange")
    public Exchange aliceExchange() {
        return ExchangeBuilder.topicExchange(EXCHANGE_NAME).durable(true).build();
    }

    @Bean("aliceQueue")
    public Queue aliceQueue() {
        return QueueBuilder.durable(QUEUE_NAME).build();
    }

    @Bean
    public Binding bindQueueExchange(@Qualifier("aliceQueue") Queue queue, @Qualifier("aliceExchange") Exchange exchange) {
        return BindingBuilder.bind(queue).to(exchange).with("alice.#").noargs();
    }


}

生产者:

MessageProvider

package com.king.alice.rabbitmq.delay.provider;

import cn.hutool.core.date.DateUtil;
import com.king.alice.common.json.JSON;
import com.king.alice.rabbitmq.config.RabbitMqConfig;
import com.king.alice.rabbitmq.delay.bean.DelayMessage;
import lombok.extern.slf4j.Slf4j;
import org.junit.Assert;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.Date;

/**
 * @author 大魔王
 */
@Slf4j
@Component
public class MessageProvider {
    @Autowired
    private final RabbitTemplate rabbitTemplate;

    public MessageProvider(RabbitTemplate rabbitTemplate) {
        this.rabbitTemplate = rabbitTemplate;
    }

    /**
     * send delay message
     */
    public void sendMessage(DelayMessage delayMessage) {
        Assert.assertNotNull(delayMessage);
        log.info(" now date {},delay {} seconds to write to the message queue", DateUtil.format(new Date(), "yyyy-MM-dd HH:mm:ss"), delayMessage.getDelay());
        rabbitTemplate.convertAndSend(RabbitMqConfig.DELAY_EXCHANGE_NAME, RabbitMqConfig.DELAY_QUEUE_ROUTING_KEY, delayMessage,
                message -> {
                    message.getMessageProperties().setExpiration(String.valueOf(delayMessage.getDelay() * 1000));
                    return message;
                });
    }

}

消费者:

package com.king.alice.rabbitmq.delay.consumer;

import cn.hutool.core.util.ObjectUtil;
import com.king.alice.common.json.JSONObject;
import com.king.alice.rabbitmq.delay.bean.AliceMessage;
import com.king.alice.rabbitmq.delay.bean.DelayMessage;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.AcknowledgeMode;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageListener;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

/**
 * @author 大魔王
 */
@Slf4j
public class MessageConsumer implements MessageListener {

    private final Map<Type, List<Strategy>> strategyMap = new ConcurrentHashMap<>();

    public MessageConsumer(ObjectProvider<List<Strategy>> stategyProvider) {
        List<Strategy> handleList = stategyProvider.getIfAvailable();
        Optional<? extends List<Strategy>> optionalStrategies = Optional.ofNullable(handleList);
        optionalStrategies.ifPresent(strategies -> strategies.stream().filter(strategy -> {
            Type genericInterface = strategy.getClass().getGenericInterfaces()[0];
            return genericInterface instanceof ParameterizedType;
        }).map(strategy -> ((ParameterizedType) strategy.getClass().getGenericInterfaces()[0]).getActualTypeArguments()[0])
                .collect(Collectors.toSet()).forEach(delayMessages -> {
                    List<Strategy> collect = strategies.stream().filter(strategy -> {
                        Type genericInterface = strategy.getClass().getGenericInterfaces()[0];
                        if (genericInterface instanceof ParameterizedType) {
                            Type actualTypeArgument = ((ParameterizedType) genericInterface).getActualTypeArguments()[0];
                            return delayMessages.getTypeName().equals(actualTypeArgument.getTypeName());
                        }
                        return false;
                    }).collect(Collectors.toList());
                    strategyMap.put(delayMessages, collect);
                }));
    }
    @Override
    public void onMessage(Message message) {
        MessageConverter messageConverter = new Jackson2JsonMessageConverter();
        DelayMessage delayMessage = (DelayMessage) messageConverter.fromMessage(message);
        List<Strategy> strategyList = strategyMap.get(delayMessage.getClass());
        if (!CollectionUtils.isEmpty(strategyList)) {
            strategyList.forEach(strategy -> strategy.handle(delayMessage));
        } else {
            log.info("Missing message processing class");
        }
    }

}

策略相关Bean,接口以及实现类

DelayMessage

package com.king.alice.rabbitmq.delay.bean;

/**
 * @author 大魔王
 */
public interface DelayMessage{
    /**
     * 获得延迟时间（单位秒）
     *
     * @return 延迟时间单位秒
     */
    int getDelay();

}

AliceMessage

package com.king.alice.rabbitmq.delay.bean;

import lombok.Getter;
import lombok.Setter;



/**
 * @author 大魔王
 */
@Getter
@Setter
public class AliceMessage implements DelayMessage {
    /**
     *  用户邮箱
     */
    String email;

    /**
     *  订单类型
     */
    String orderType;

    /**
     *  执行次数
     */
    Integer dealCount;

    /**
     *  延时秒数
     */
    int delay;

    @Override
    public int getDelay() {
        return this.delay;
    }

    public void setDelay(int delay) {
        this.delay = delay;
    }
}

UserMessage

package com.king.alice.rabbitmq.delay.bean;

import lombok.Getter;
import lombok.Setter;

/**
 * @author 大魔王
 */
@Getter
@Setter
public class UserMessage implements DelayMessage{
    /**
     *  用户
     */
    String username;

    /**
     *  token
     */
    String token;

    /**
     *  执行次数
     */
    Integer dealCount;

    /**
     *  延时秒数
     */
    int delay;

    @Override
    public int getDelay() {
        return this.delay;
    }

    public void setDelay(int delay) {
        this.delay = delay;
    }
}

Strategy

package com.king.alice.rabbitmq.delay.consumer;

import com.king.alice.rabbitmq.delay.bean.DelayMessage;

/**
 * @author 大魔王
 */
public interface Strategy<T extends DelayMessage> {

    /**
     * 处理消息的方法
     *
     * @param delayMessage 收到的消息
     */
    void handle(T delayMessage);
}

AliceMessageHandler

package com.king.alice.rabbitmq;

import com.king.alice.common.json.JSON;
import com.king.alice.common.json.JSONObject;
import com.king.alice.rabbitmq.delay.bean.AliceMessage;
import com.king.alice.rabbitmq.delay.consumer.Strategy;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * @author 大魔王
 */
@Component
@Slf4j
public class AliceMessageHandler implements Strategy<AliceMessage> {
    @Override
    public void handle(AliceMessage delayMessage) {
        log.info("AliceMessage响应体{}", JSONObject.parseObject(JSON.toJSONString(delayMessage)));
    }
}

UserMessageHandler

package com.king.alice.rabbitmq;

import com.king.alice.common.json.JSON;
import com.king.alice.common.json.JSONObject;
import com.king.alice.rabbitmq.delay.bean.UserMessage;
import com.king.alice.rabbitmq.delay.consumer.Strategy;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * @author 大魔王
 */
@Slf4j
@Component
public class UserMessageHandler implements Strategy<UserMessage> {

    @Override
    public void handle(UserMessage delayMessage) {
        log.info("UserMessage响应体{}", JSONObject.parseObject(JSON.toJSONString(delayMessage)));
    }
}

接下来我们写个controller测试一下

SysAccountController

package com.king.alice.manage.sys.controller;

import cn.hutool.core.date.DateUtil;
import com.king.alice.manage.sys.entity.SysAccount;
import com.king.alice.manage.sys.service.SysAccountService;
import com.king.alice.rabbitmq.delay.bean.AliceMessage;
import com.king.alice.rabbitmq.delay.bean.UserMessage;
import com.king.alice.rabbitmq.delay.provider.MessageProvider;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;
import java.util.Date;

/**
 * 账号表(SysAccount)表控制层
 *
 * @author makejava
 * @since 2023-08-09 11:40:16
 */
@RestController
@Slf4j
public class SysAccountController {
    /**
     * 服务对象
     */
    @Resource
    private SysAccountService sysAccountService;

    @Autowired
    private MessageProvider messageProvider;

    @PostMapping("/send-alice-message")
    public String sendMsg(@RequestBody AliceMessage aliceMessage) {
        messageProvider.sendMessage(aliceMessage);
        log.info("当前时间：{},收到aliceMessage请求，msg:{}", DateUtil.format(new Date(), "yyyy-MM-dd HH:mm:ss"), aliceMessage);
        return "success";
    }

    @PostMapping("/send-user-message")
    public String sendMsg(@RequestBody UserMessage userMessage) {
        messageProvider.sendMessage(userMessage);
        log.info("当前时间：{},收到userMessage请求，msg:{}", DateUtil.format(new Date(), "yyyy-MM-dd HH:mm:ss"), userMessage);
        return "success";
    }
}