秒杀功能

补充：

实际项目中的主键不能用自增id，我们可以用snowflake算法。

参考：http://mp.weixin.qq.com/s/bIkdcYo32yTEOGn0t8ABeg

核心代码：

@Controller
@RequestMapping("/miaosha")
public class MiaoshaController {

    @Autowired
    MiaoshaUserService userService;
    
    @Autowired
    RedisService redisService;
    
    @Autowired
    GoodsService goodsService;
    
    @Autowired
    OrderService orderService;
    
    @Autowired
    MiaoshaService miaoshaService;
    
    @RequestMapping("/do_miaosha")
    public String list(Model model,MiaoshaUser user,
            @RequestParam("goodsId")long goodsId) {
        model.addAttribute("user", user);
        if(user == null) {
            return "login";
        }
        //判断库存
        GoodsVo goods = goodsService.getGoodsVoByGoodsId(goodsId);
        int stock = goods.getStockCount();
        if(stock <= 0) {
            model.addAttribute("errmsg", CodeMsg.MIAO_SHA_OVER.getMsg());
            return "miaosha_fail";
        }
        //判断是否已经秒杀到了
        MiaoshaOrder order = orderService.getMiaoshaOrderByUserIdGoodsId(user.getId(), goodsId);
        if(order != null) {
            model.addAttribute("errmsg", CodeMsg.REPEATE_MIAOSHA.getMsg());
            return "miaosha_fail";
        }
        //减库存 下订单 写入秒杀订单
        OrderInfo orderInfo = miaoshaService.miaosha(user, goods);
        model.addAttribute("orderInfo", orderInfo);
        model.addAttribute("goods", goods);
        return "order_detail";
    }
}