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

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

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

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;

@Service
public 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");
    }
}

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;

@Component
public 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"));
    }
}

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

userGoodsProducer.sendMessage(userGoods);

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;

@Service
public 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;
    }
}