Spring框架-事务管理注意事项

常见事务问题

事务不起作用
- 可能是配置不起效，如扫描问题
事务自动提交了（批量操作中）
- 可能是在没事务的情况下，利用了数据库的隐式提交

事务配置说明

通常情况下我们的Spring Component扫描分为两部分，一部分是Spring Servlet(MVC)，一部分是其他Context Config的内容。主要扫描Annotation定义，包括@Controller、@Autowired、@Resource、@Service、@Component、@Repository等。

Spring Servlet部分的扫描配置可以通过web.xml中DispatchServlet的init-param节点配置确定。

Context Config部分的扫描配置为非以上配置的其他Spring配置文件确定。

为了能够使用事务，需要防止因Spring Servlet的扫描导致@Service事务配置失效。可以调整DispatchServlet中的配置文件，排除对@Service的扫描。

配置如下：

<context:component-scan base-package="com.jiuyescm.xxx">
	<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service" />
</context:component-scan>

如何通过日志判断事务是否已经被Spring所管理？

在logback或者log4j中对org.springframework.aop、org.springframework.transaction、org.springframework.jdbc、org.mybatis.spring.transaction进行DEBUG级别日志跟踪（开发期）

查看日志中是否有事务管理、开启、提交、回滚等字符，如：

DEBUG o.m.spring.transaction.SpringManagedTransaction - JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@28cfe912] will be managed by Spring

没有被控制的时候，日志如下：

DEBUG o.m.spring.transaction.SpringManagedTransaction - JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@28cfe912] will not be managed by Spring

如何通过程序判断是否存在事务？

boolean flag = TransactionSynchronizationManager.isActualTransactionActive();

返回true，则在事务控制下，否则不在控制下

什么时候做了隐式提交？

在没有容器事务的情况下，系统会尝试隐时提交。

开发建议：

所有Service代码中设置Class级别的@Transactional，并设置为只读，开发时可以很容易发现误数据库操作的动作。如：@Transactional(readOnly=true)。
所有Service代码中Public的方法设置@Transactional，并根据实际情况设置Propagation，可以设置为REQUIRED。
对于有异常产生可能的情况下，根据情况选择合适的rollbackFor，默认情况下可以设置对Exception.class或BizException.class进行控制。
尽可能减少嵌套的使用方法（Service call Service），采用传统的Controller-》Service-》Repository(DAO)的模型。

如果需要深入了解Transaction的流程，请自行翻阅和跟踪Spring和Mybatis相关代码。

以下是嵌套事务的各种情况下的执行结果（前提数据库的AutoCommit为true）

编号	External（Service）	Internal（Service）	Result	Memo
1	No Transactional	No Transactional	All Committed	Auto Commit = True
2	No Transactional	Class Level ReadOnly Transactional	External Committed Internal TransientDataAccessResourceException	Can’t update table
3	No Transactional	Transactional(REQUIRED)	All Committed
4	No Transactional	Transactional(REQUIRES_NEW)	All Committed
5	No Transactional	Transactional(SUPPORTS)	All Committed
6	No Transactional	Transactional(MANDATORY)	External Committed Internal IllegalTransactionStateException	Must under transaction
7	No Transactional	Transactional(NOT_SUPPORTED)	All Committed
8	No Transactional	Transactional(NEVER)	All Committed
9	No Transactional	Transactional(NESTED)	All Committed
10	No Transactional	Transactional(REQUIRED) rollackFor=Exception.class IOException	External Committed Internal Rollbacked
11	No Transactional	Transactional(REQUIRED) rollbackFor=RuntimeException.class IOException	All Committed
12	No Transactional	Transactional(REQUIRED)	rollbackFor=Exception.class RuntimeException	External Committed Internal Rollbacked
13	No Transactional	Transactional(REQUIRED)	rollbackFor=RuntimeException.class RuntimeException	External Committed Internal Rollbacked
14	Class Level ReadOnly Transactional	No Transactional	External TransientDataAccessResourceException	Can’t update table
15	Class Level ReadOnly Transactional	Class Level ReadOnly Transactional	External TransientDataAccessResourceException	Can’t update table
16	Transactional(REQUIRED)	No Transactional	All Committed
17	Transactional(REQUIRES_NEW)	No Transactional	All Committed
18	Transactional(SUPPORTS)	No Transactional	All Committed
19	Transactional(MANDATORY)	No Transactional	External IllegalTransactionStateException	Must under transaction
20	Transactional(NOT_SUPPORTED)	No Transactional	All Committed
21	Transactional(NEVER)	No Transactional	All Committed
22	Transactional(NESTED)	No Transactional	All Committed
23	Transactional(REQUIRED)	Transactional(REQUIRED)	All Committed
24	Transactional(REQUIRED)	Transactional(REQUIRES_NEW)	All Committed
25	Transactional(REQUIRED)	Transactional(SUPPORTS)	All Committed
26	Transactional(REQUIRED)	Transactional(MANDATORY)	All Committed
27	Transactional(REQUIRED)	Transactional(NOT_SUPPORTED)	All Committed
28	Transactional(REQUIRED)	Transactional(NEVER)	External Rollbacked Internal IllegalTransactionStateException	Must under transaction
29	Transactional(REQUIRED)	Transactional(NESTED)	All Committed
30	Transactional(REQUIRED)	rollackFor=Exception.class Transactional(REQUIRED) rollackFor=Exception.class IOException	All Rollbacked
31	Transactional(REQUIRED)	rollackFor=Exception.class Transactional(REQUIRED) rollbackFor=RuntimeException.class IOException	All Rollbacked
32	Transactional(REQUIRED)	rollackFor=RuntimeException.class Transactional(REQUIRED) rollackFor=Exception.class IOException	All Rollbacked UnexpectedRollbackException
33	Transactional(REQUIRED)	rollackFor=RuntimeException.class Transactional(REQUIRED) rollbackFor=RuntimeException.class IOException	All Committed
34	Transactional(REQUIRED)	rollackFor=Exception.class Transactional(REQUIRED) rollackFor=Exception.class RuntimeException	All Rollbacked
35	Transactional(REQUIRED)	rollackFor=Exception.class Transactional(REQUIRED) rollbackFor=RuntimeException.class RuntimeException	All Rollbacked
36	Transactional(REQUIRED)	rollackFor=RuntimeException.class Transactional(REQUIRED) rollackFor=Exception.class RuntimeException	All Rollbacked
37	Transactional(REQUIRED)	rollackFor=RuntimeException.class Transactional(REQUIRED) rollbackFor=RuntimeException.class RuntimeException	All Rollbacked
38	Transactional(REQUIRED)	rollackFor=Exception.class Transactional(REQUIRED) rollackFor=Exception.class IOException Catch IOException	All Committed
39	Transactional(REQUIRED)	rollackFor=Exception.class Catch IOExceptio Transactional(REQUIRED) rollbackFor=Exception.class IOException	All Rollbacked UnexpectedRollbackException
40	Transactional(REQUIRED)	rollackFor=Exception.class Catch IOException Transactional(REQUIRED) rollbackFor=RuntimeException.class IOException	All Committed

其他情况按照事务是否开启和是否抛出（捕获）对应异常来判断结果。