Question

我有这样的代码：

@Transactional(rollbackOn = RuntimeException.class)
    synchronized public void transfer(@NonNull final TransferModel transferModel) {
        log.info("Start processing money transfer from user: {} to receiver: {}. Transfer amount: {}", transferModel.getOwnerId(), transferModel
                .getReceiverId(), transferModel.getAmount());

        final AccountEntity ownerAccount = findByOwner(transferModel.getOwnerId());
        final AccountEntity receiverAccount = findByOwner(transferModel.getReceiverId());

        log.info("Owner balancer before transfer: {}. Receiver balance before transfer {}", ownerAccount.getBalance(), receiverAccount.getBalance());

        if (ownerAccount.getBalance().compareTo(transferModel.getAmount()) < 0) {
            throw new IllegalArgumentException("Owner has insufficient amount of money");
        }

        withdrawFromOwnerAccount(ownerAccount, transferModel.getAmount());
        depositToReceiverAccount(receiverAccount, transferModel.getAmount());

        log.info("Transfer money finished successful");
        log.info("Owner balancer after transfer: {}. Receiver balance after transfer {}", ownerAccount.getBalance(), receiverAccount.getBalance());
    }

简单的方法，从所有者采取moeny并传递给接收者。这种解决方案很幼稚，因为它不能同时处理多个转移。如何确保此方法可以处理多个请求并在并发环境中安全？

Answer 1

正如ghostCat所说，我们对你的环境并不熟悉，所以如果任何“看起来天真”的方法都有副作用，我们就不会知道了。

那就是说，假设这是一个非常简单直接的代码，方法名称反映了他们正在做的事情，我认为我们不必同步所有方法，而只是关键部分：

withdrawFromOwnerAccount(ownerAccount, transferModel.getAmount());
depositToReceiverAccount(receiverAccount, transferModel.getAmount());

我们可以使用帐户同步此部分：

synchronized (ownerAccount) {
    withdrawFromOwnerAccount(ownerAccount, transferModel.getAmount());
}
synchronized (receiverAccount) {
    depositToReceiverAccount(receiverAccount, transferModel.getAmount());
}

通过这样做，我们可以并行执行此方法，并仅在给予者/接收者已经处于执行另一个事务的过程中时锁定线程。

注意：为了应用这种方法，您必须确保同一帐户没有两个对象！

Java，转账服务和并发问题

1 个答案: