关于spring:五Spring事务提交

接第 2 节内容，这是第 6 点具体解析

事务提交逻辑如下：

1. 判断事务是否曾经实现，如果实现抛出异样
2. 判断事务是否曾经被标记成回滚，则执行回滚操作
3. 嵌入事务标记回滚，如果嵌入事务抛出了异样执行了回滚，然而在调用方把嵌入事务的异样个捕捉没有抛出，就会执行这一步。
4. 提交事务

代码如下：

@Override
public final void commit(TransactionStatus status) throws TransactionException {
    //1. 判断事务是不是曾经实现
    if (status.isCompleted()) {
        throw new IllegalTransactionStateException("Transaction is already completed - do not call commit or rollback more than once per transaction");
    }

    DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status;
    //2. 如果在事务链中曾经被标记回滚，那么不会尝试提交事务，间接回滚，不过我没找到在哪设置这个值
    if (defStatus.isLocalRollbackOnly()) {if (defStatus.isDebug()) {logger.debug("Transactional code has requested rollback");
        }
        processRollback(defStatus);
        return;
    }
    //3. shouldCommitOnGlobalRollbackOnly() 默认返回 false，isGlobalRollbackOnly 是在嵌入事务回滚的时候赋值的
    if (!shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) {if (defStatus.isDebug()) {logger.debug("Global transaction is marked as rollback-only but transactional code requested commit");
        }
        processRollback(defStatus);
        // Throw UnexpectedRollbackException only at outermost transaction boundary
        // or if explicitly asked to.
        if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) {
            throw new UnexpectedRollbackException("Transaction rolled back because it has been marked as rollback-only");
        }
        return;
    }
    //4. 提交事务
    processCommit(defStatus);
}