【黑马点评】使用RabbitMQ实现消息队列——2.使用RabbitMQ监听秒杀下单

2 使用RabbitMQ实现消息队列

2.1 修改\hm-dianping\pom.xmlpom.xml文件

添加RabbitMQ的环境

<!-- RabbitMQ-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-amqp</artifactId>
</dependency>

2.2 修改Resource下的application.yaml文件

添加RabbitMQ的配置信息

spring:
  rabbitmq:
    host: 127.0.0.1 # IP地址
    port: 5672 # 端口号
    username: hmdianping # 用户名
    password: 123456 # 密码
    listener:
      simple:
        concurrency: 1
        max-concurrency: 1
        acknowledge-mode: manual
        prefetch: 1

主启动类标注@EnableRabbit开启消息队列的监听功能

在这里插入图片描述

2.3 配置RabbitMQ,创建交换机和消息队列，将二者绑定

创建direct类型的交换机以及一个名为seckill.order.queue的消息队列，然后将二者绑定.之后发往该交换机且路由键为seckill.order的消息都会转发seckill.order.queue

具体而言，在hm-dianping.src.main.java.com.hmdp.config下新建RabbitMQConfig文件

文件内容如下

package com.hmdp.config;

import com.hmdp.entity.VoucherOrder;
import com.hmdp.service.IVoucherOrderService;
import com.rabbitmq.client.Channel;
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.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.annotation.Resource;
import java.io.IOException;

@Configuration
public class RabbitMQConfig {

    @Resource
    IVoucherOrderService voucherOrderService;

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "direct.seckill.queue"),
            key = "direct.seckill",
            exchange = @Exchange(name = "hmdianping.direct", type = ExchangeTypes.DIRECT)
    ))
    public void recieveMessage(Object message){
        System.out.println("监听到了"+message);
    }


    @Bean
    public MessageConverter messageConverter() {
        return new Jackson2JsonMessageConverter();
    }
}

2.3.1 测试监听消息

在Test中添加发送消息的方法，指定交换机hmdianping.direct 为和路由键 direct.seckill。

    @Resource
    RabbitTemplate rabbitTemplate;
    @Test
    public void testSendMessage(){
        rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill","测试发送消息");
    }

先运行Test方法

在这里插入图片描述

之后运行启动类HmDianPingApplication

发现监听到了，说明连接成功。

在这里插入图片描述

2.3.2 修改秒杀下单业务(VoucherOrderServiceImpl中的seckillVoucher方法)

注入RabbitTemplate类
在认定有抢购资格后，直接向seckill.direct交换机发送消息，内容包含voucherId、userId、orderId

    @Resource
    RabbitTemplate rabbitTemplate;
    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.执行lua脚本，判断当前用户的购买资格
        Long userId = UserHolder.getUser().getId();
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString());
        if (result != 0) {
            //2.不为0说明没有购买资格
            return Result.fail(result==1?"库存不足":"不能重复下单");
        }
        //3.走到这一步说明有购买资格，将订单信息存到消息队列
        VoucherOrder voucherOrder = new VoucherOrder();
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        voucherOrder.setUserId(UserHolder.getUser().getId());
        voucherOrder.setVoucherId(voucherId);
        //存入消息队列等待异步消费
        rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill",voucherOrder);
        return Result.ok(orderId);
    }

此时VoucherOrderServiceImpl文件内容如下

package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.*;
import org.springframework.amqp.rabbit.core.RabbitTemplate;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private IVoucherOrderService iVoucherOrderService;

    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;


    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);

    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();


    @Transactional
    public void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.所有信息从当前消息实体中拿
        Long voucherId = voucherOrder.getVoucherId();
        //2.扣减库存
        boolean success = seckillVoucherService.update().setSql("stock=stock-1")
                .eq("voucher_id", voucherId)
                //======判断当前库存是否大于0就可以决定是否能抢池子中的券了
                .gt("stock", 0)
                .update();
        //3.创建订单
        if(success) save(voucherOrder);
    }

    @Resource
    RabbitTemplate rabbitTemplate;
    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.执行lua脚本，判断当前用户的购买资格
        Long userId = UserHolder.getUser().getId();
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString());
        if (result != 0) {
            //2.不为0说明没有购买资格
            return Result.fail(result==1?"库存不足":"不能重复下单");
        }
        //3.走到这一步说明有购买资格，将订单信息存到消息队列
        VoucherOrder voucherOrder = new VoucherOrder();
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        voucherOrder.setUserId(UserHolder.getUser().getId());
        voucherOrder.setVoucherId(voucherId);
        //存入消息队列等待异步消费
        rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill",voucherOrder);
        return Result.ok(orderId);
    }



    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder){
        // 5.一人一单逻辑
        // 5.1.用户id
        Long userId = voucherOrder.getId();

        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder).count();
        // 5.2.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            log.error("用户已经购买过一次！");
            return ;
        }

        //6.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock= stock -1") // set stock = stock -1
                .eq("voucher_id", voucherOrder)
                .gt("stock",0)// where id = ? and stock > 0
                .update();
        if (!success) {
            //扣减库存
            log.error("库存不足！");
            return ;
        }


        save(voucherOrder);

    }
}

2.3.3 监听秒杀成功订单

监听seckill.order.queue队列的信息并且创建订单到数据库，当创建完成时手动ack

RabbitMQConfig中的recieveMessage修改为

    public void recieveMessage(Message message, Channel channel, VoucherOrder voucherOrder){
        try {
            voucherOrderService.handleVoucherOrder(voucherOrder);
            channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        System.out.println("监听到了"+message);
    }

此时，文件内容为。

package com.hmdp.config;

import com.hmdp.entity.VoucherOrder;
import com.hmdp.service.IVoucherOrderService;
import com.rabbitmq.client.Channel;
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.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.annotation.Resource;
import java.io.IOException;

@Configuration
public class RabbitMQConfig {

    @Resource
    IVoucherOrderService voucherOrderService;

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "direct.seckill.queue"),
            key = "direct.seckill",
            exchange = @Exchange(name = "hmdianping.direct", type = ExchangeTypes.DIRECT)
    ))
/*    public void recieveMessage(Object message){
        System.out.println("监听到了"+message);
    }*/
    public void recieveMessage(Message message, Channel channel, VoucherOrder voucherOrder){
        try {
            voucherOrderService.handleVoucherOrder(voucherOrder);
            channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        System.out.println("监听到了"+message);
    }



    @Bean
    public MessageConverter messageConverter() {
        return new Jackson2JsonMessageConverter();
    }
}