Spring 中 @Transactional and synchronized同时存在的问题

Spring 中 @Transactional and synchronized同时存在的问题

控制器代码

`

@PostMapping("/addExchange")
@ApiOperation(value = "兑换")
public R addExchange(@RequestBody AddExchangeDTO req){
    AppUser user = ThreadUtil.getUser();
    //校验交易密码
    iAppUserService.checkTradePassword(user.getTradePassword(),req.getTradePassword());
    //兑换
    return R.status(hisExchangeService.addExchange(req,user.getId()));
}

`

1、正确的处理方式：事务中可以加锁

`

@Override
@Transactional(rollbackFor = Exception.class)
public boolean addExchange(AddExchangeDTO req, Integer userId) {
    AppUser my = appUserService.getById(userId);
    //操作价值
    BigDecimal worth = new BigDecimal(req.getWorth());
    //市价
    BigDecimal nowPrice = hisIconPriceService.getNowPrice();
    doExchange(req.getType(), my, worth, nowPrice);
    return true;
}

@Override
//@Transactional(rollbackFor = Exception.class)
public synchronized void doExchange(Integer type, AppUser my, BigDecimal worth, BigDecimal nowPrice) {
    //XU 兑换 U
    if (type.equals(0)) {
        XU_To_U(worth, my.getWalletXu(), nowPrice, my.getWalletId(), my.getId());
    }
    //U 兑换 XU
    if (type.equals(1)) {
        U_To_XU(worth, my.getWalletUsdt(), nowPrice, my.getWalletId());
    }
}

`

2、错误的处理方式：锁中加事务,网络上很多人介绍这种处理方式

`

@Override
public synchronized boolean addExchange(AddExchangeDTO req, Integer userId) {
    AppUser my = appUserService.getById(userId);
    //操作价值
    BigDecimal worth = new BigDecimal(req.getWorth());
    //市价
    BigDecimal nowPrice = hisIconPriceService.getNowPrice();
    doExchange(req.getType(), my, worth, nowPrice);
    return true;
}

@Override
@Transactional(rollbackFor = Exception.class)
public void doExchange(Integer type, AppUser my, BigDecimal worth, BigDecimal nowPrice) {
    //XU 兑换 U
    if (type.equals(0)) {
        XU_To_U(worth, my.getWalletXu(), nowPrice, my.getWalletId(), my.getId());
    }
    //U 兑换 XU
    if (type.equals(1)) {
        U_To_XU(worth, my.getWalletUsdt(), nowPrice, my.getWalletId());
    }
}

`

说明：

-- U_To_XU 或 XU_To_U 会做U的转换 并做记录;
-- 第一种方式会保证数据的一致性。
-- 第二种方式无法保证数据的一致性；当部分业务抛出业务异常时，事务并没有回滚。