玩转 Spring Boot 应用篇（引入RabbitMQ解决店铺下单峰值问题）（十八）

0.1. 回顾（菜菜的店铺目前存在的问题）

上次分享通过集成 Redis 技术组件，让请求不再直接查询数据库，而是优先从 Redis 查询商品信息，进而来解决数据库高并发读的问题。

但是此时的技术实现，当面对瞬间特高的访问流量峰值时，会导致服务或者数据库宕机，那么面对流量峰值，该如何解决呢？

坊间，多数是引入 MQ 来削峰，本次采取集成 RabbitMQ 来支持。

1. 菜菜的店铺技术升级：集成 RabbitMQ

有关 Spring Boot 集成 RabbitMQ 的详细操作步骤，可以参考历史文章《玩转 Spring Boot 集成篇（RabbitMQ）（六）》，本次采取集成 RabbitMQ 来缓解流量峰值的问题。

引入依赖

代码语言：javascript复制

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

添加 RabbitMQ 配置

代码语言：javascript复制

## RabbitMQ 配置# RabbitMQ服务的地址spring.rabbitmq.host=localhostspring.rabbitmq.port=5672spring.rabbitmq.username=guestspring.rabbitmq.password=guest# RabbitMQ 服务创建的虚拟主机(非必须)spring.rabbitmq.virtual-host=/

2. 创建商品购买记录代码改造

可以考虑对同步保存商品购买记录的操作进行异步化保存，这样可以提高请求的响应速度，提高用户的使用体验，减少了流量高峰对数据库的压力。

创建常量类

商品购买记录生产者（UserGoodsProducer）

代码语言：javascript复制

package org.growup.caicaishop.mq;
import org.growup.caicaishop.entity.UserGoods;import org.growup.caicaishop.utils.Constant;import org.springframework.amqp.rabbit.core.RabbitTemplate;import org.springframework.stereotype.Service;
import javax.annotation.Resource;import java.util.logging.Logger;
@Servicepublic class UserGoodsProducer {
    private final Logger logger = Logger.getLogger("UserGoodsProducer");
    @Resource    private RabbitTemplate rabbitTemplate;
    public void sendMessage(UserGoods userGoods) {        logger.info("【生产者】- 待保存的商品购买记录 - "   userGoods);        rabbitTemplate.convertAndSend(Constant.USER_GOODS_QUEUE, userGoods);        logger.info("【生产者】- 商品购买记录"   userGoods.getGoodsId()   "发送 MQ 完成");    }}

商品购买记录消费者（UserGoodsConsumer）

代码语言：javascript复制

package org.growup.caicaishop.mq;
import org.growup.caicaishop.entity.UserGoods;import org.growup.caicaishop.service.UserGoodsService;import org.growup.caicaishop.utils.Constant;import org.springframework.amqp.rabbit.annotation.Queue;import org.springframework.amqp.rabbit.annotation.RabbitHandler;import org.springframework.amqp.rabbit.annotation.RabbitListener;import org.springframework.stereotype.Component;
import javax.annotation.Resource;import java.util.logging.Logger;
@Componentpublic class UserGoodsConsumer {
    private final Logger logger = Logger.getLogger("UserGoodsConsumer");
    @Resource    private UserGoodsService userGoodsService;
    @RabbitHandler    @RabbitListener(queuesToDeclare = @Queue(Constant.USER_GOODS_QUEUE))    public void process(UserGoods userGoods) {        // 保存商品购买记录信息        int saveRes = userGoodsService.save(userGoods);        logger.info("【消费者】商品购买记录创建："   (saveRes != 0 ? "成功" : "失败"));    }}

商品购买 Service 修改

代码语言：javascript复制

int saveRes = userGoodsDao.insert(userGoods); logger.info("插入购买记录："   saveRes);

修改为发送 MQ 消息：

代码语言：javascript复制

userGoodsProducer.sendMessage(userGoods);

详细代码如下：

代码语言：javascript复制

package org.growup.caicaishop.service.impl;
import org.growup.caicaishop.dao.GoodsDao;import org.growup.caicaishop.entity.Goods;import org.growup.caicaishop.entity.UserGoods;import org.growup.caicaishop.mq.UserGoodsProducer;import org.growup.caicaishop.service.PurchaseService;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Isolation;import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;import java.sql.Timestamp;import java.util.logging.Logger;
import static org.growup.caicaishop.utils.Constant.GOODS_LIST_CACHE_KEY;
@Servicepublic class PurchaseServiceImpl implements PurchaseService {
    private final Logger logger = Logger.getLogger("PurchaseServiceImpl");
    @Resource    private GoodsDao goodsDao;
    @Resource    private RedisTemplate redisTemplate;
    @Resource    private UserGoodsProducer userGoodsProducer;
    @Override    @Transactional(isolation = Isolation.READ_COMMITTED)    public boolean purchase(Integer userId, Integer goodsId, int quantity) {        // 加入尝试固定次数限制        for (int i = 0; i < 3; i  ) {            Goods goodsInfo = goodsDao.getGoodsById(goodsId);            if (goodsInfo.getStock() < quantity) {                // 库存不足                logger.info("库存不足: "   goodsInfo.getStock());                return false;            }
            //扣减库存            int res = goodsDao.reduceStock(goodsId, quantity, goodsInfo.getVersion());            logger.info("扣减库存结果："   res);            if (res == 0) {                logger.info("数据被修改，本次购买失败，继续尝试");                continue;            }            //扣减库存成功，则更新 redis 中缓存的商品信息            redisTemplate.opsForHash().put(GOODS_LIST_CACHE_KEY, goodsId, goodsDao.getGoodsById(goodsId));            logger.info("更新缓存中的商品信息："   goodsId   "成功");            //插入购买记录            UserGoods userGoods = new UserGoods();            userGoods.setUserId(userId);            userGoods.setGoodsId(goodsId);            userGoods.setQuantity(quantity);            userGoods.setState(1);            userGoods.setCreateTime(new Timestamp(System.currentTimeMillis()));            //int saveRes = userGoodsDao.insert(userGoods);            //logger.info("插入购买记录："   saveRes);            userGoodsProducer.sendMessage(userGoods);            return true;        }        logger.info("重试 3 次后依然失败");        return false;    }}

3. 验证

运行菜菜的店铺服务，然后选择钟意的商品点击“买它”。