L1uxiaolin commented on issue #615:
URL:
https://github.com/apache/incubator-seata-samples/issues/615#issuecomment-2027957300
> ```
> public boolean prepareMinus(BusinessActionContext businessActionContext,
final String accountNo,
> final double amount) {
> //分布式事务ID
> final String xid = businessActionContext.getXid();
>
> return fromDsTransactionTemplate.execute(new
TransactionCallback<Boolean>() {
>
> @Override
> public Boolean doInTransaction(TransactionStatus status) {
> try {
> //校验账户余额
> Account account =
fromAccountDAO.getAccountForUpdate(accountNo);
> if (account == null) {
> throw new RuntimeException("账户不存在");
> }
> if (account.getAmount() - amount < 0) {
> throw new RuntimeException("余额不足");
> }
> //冻结转账金额
> double freezedAmount = account.getFreezedAmount() +
amount;
> account.setFreezedAmount(freezedAmount);
> fromAccountDAO.updateFreezedAmount(account);
> System.out.println(String
> .format("prepareMinus account[%s] amount[%f], dtx
transaction id: %s.", accountNo, amount,
> xid));
> return true;
> } catch (Throwable t) {
> t.printStackTrace();
> status.setRollbackOnly();
> return false;
> }
> }
> });
> }
> ```
>
> 这段代码中对FreezedAmount的操作有何意义？
不冻结的话，可能存在超出余额的转账事务存在。比如余额是100，A事务转50，B事务转100，这个时候B事务只会看到余额有100，不清楚其他事务是否也在转账中。加上第二阶段又必须成功，会导致两笔都成功。
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