Redis高并发场景下秒杀超卖解决方案(秒杀场景)

/**
 * @Author oldlu
 */
@Service
@Transactional  //控制事务
public class OrderServiceImpl implements OrderService {

    @Autowired
    private StockMapper stockMapper;

    private OrderMapper orderMapper;

    //在非并发情况下无问题
    @Override
    public Integer kill(Integer id) {
        //根据商品id校验库存是否还存在
        Stock stock = stockMapper.checkStock(id);
        //当已售和库存相等就库存不足了
        if(stock.getSale().equals(stock.getCount())){
            throw new RuntimeException("库存不足!");
        }else{
            //扣除库存  (已售数量+1)
            stock.setSale(stock.getSale()+1);
            stockMapper.updateSale(stock);   //更新信息
            //创建订单
            Order order = new Order();
            order.setSid(stock.getId()).setName(stock.getName()).setCreateDate(new Date());
            orderMapper.createOrder(order); //创建订单
            return order.getId();   //mybatis主键生成策略 直接返回创建的id
        }
    }
}

/**
 * @Author oldlu
 */
@RestController
@RequestMapping("/stock")
public class StockController {
    @Autowired
    private OrderService orderService;
    //开发秒杀方法
    @GetMapping("/kill/{id}")
    public String kill(@PathVariable("id") Integer id){
        System.out.println("秒杀商品的ID=====================>"+id);
        try {
            //根据秒杀商品id调用秒杀业务
            Integer orderId = orderService.kill(id);
            return "秒杀成功,订单ID为："+String.valueOf(orderId);
        }catch (Exception e){
            e.printStackTrace();
            return e.getMessage();
        }
    }
}

/**
 * @Author oldlu
 */
@RestController
@RequestMapping("/stock")
public class StockController {

    @Autowired
    private OrderService orderService;

    //开发秒杀方法
    @GetMapping("/kill/{id}")
    public String kill(@PathVariable("id") Integer id){
        System.out.println("秒杀商品的ID=====================>"+id);
        try {
            //使用悲观锁
            synchronized (this){
                //根据秒杀商品id调用秒杀业务
                Integer orderId = orderService.kill(id);
                return "秒杀成功,订单ID为："+String.valueOf(orderId);
            }
        }catch (Exception e){
            e.printStackTrace();
            return e.getMessage();
        }
    }

}

    /**
     * 扣除库存
     * @param stock
     */
    public void updateSale(Stock stock){
        //扣除库存  (已售数量+1)
        stock.setSale(stock.getSale()+1);
        stockMapper.updateSale(stock);   //更新信息
    }

/**
 * 扣除库存
 * @param stock
 */
public void updateSale(Stock stock){
    //在sql层面完成销量+1 和 版本号 +1 并且根据商品id和版本号同时查询更新的商品
    Integer updRows = stockMapper.updateSale(stock);   //更新信息
    if(updRows == 0){   //代表没有拿到版本号
        throw new RuntimeException("抢购失败,请重试！");
    }
}