库存售罄方案

• 库存售罄标识
• 售罄后不操作后续流程
• 售罄后通知各系统售罄
• 回补上新

库存售罄方案实现

库存售罄标识

• 当扣减完库存后，库存为 0，则打上库存售罄标识；

@Override
@Transactional
public boolean decreaseStock(Integer itemId, Integer amount) {
    long result = redisTemplate.opsForValue().increment("promo_item_stock_" + itemId, amount * -1);
    if (result > 0) {
        return true;
    } else if (result == 0) {
        redisTemplate.opsForValue().set("promo_item_stock_invalid_" + itemId, "true");
        return true;
    } else {
        redisTemplate.opsForValue().increment("promo_item_stock_" + itemId, amount);
        return false;
    }
}

售罄后不操作后续流程

• 生成库存流水之前，前看看是否存在售罄标识，如果存在，就不走后面的流程，直接返回前端；

@RequestMapping(value = "/createorder", method = {RequestMethod.POST}, consumes = {CONTENT_TYPE_FORMED})
@ResponseBody
public CommonReturnType createOrder(@RequestParam(name = "itemId") Integer itemId,
                                    @RequestParam(name = "amount") Integer amount,
                                    @RequestParam(name = "promoId", required = false) Integer promoId) throws BusinessException {
    String token = httpServletRequest.getParameterMap().get("token")[0];
    if (StringUtils.isEmpty(token)) {
        throw new BusinessException(EmBusinessError.USER_NOT_LOGIN, "用户还未登录，不能下单");
    }
    UserModel userModel = (UserModel) redisTemplate.opsForValue().get(token);
    if (userModel == null) {
        throw new BusinessException(EmBusinessError.USER_NOT_LOGIN, "用户还未登录，不能下单");
    }

    // 判断库存是否已经售罄，若对应的售罄 key 存在，则直接返回下单失败
    if (redisTemplate.hasKey("promo_item_stock_invalid_" + itemId)) {
        throw new BusinessException(EmBusinessError.STOCK_NOT_ENOUGH);
    }

    String stockLogId = itemService.initStockLog(itemId, amount);
    if(!mqProducer.transactionAsyncReduceStock(userModel.getId(), promoId, itemId, amount, stockLogId)) {
        throw new BusinessException(EmBusinessError.UNKNOWN_ERROR, "下单失败");
    }
    return CommonReturnType.create(null);
}