数据库引擎不支持事务
在MySQL数据库中有几种引擎(InnoDB,MyISAM,Memory等等),仅仅InnoDB支持事务,如果数据库底层都不支持事务的话,那么再怎么折腾都是白搭.
@transactional加在private方法上
@Transactional只能加在public方法上,如果需要在private方法中加入事务,可以使用Aspect配transactionManager使用.
本类方法调本类另一个方法
例如:
@Service
public class UserServiceImpl implements UserService {
@Transactional
public void update(User user) {
//check
updateUserInfo(user);
}
@Transactional(propagation = Propagation.REQUIRES_NEW)
public void updateUser(User user) {
// update user
}
}
@Transactional(propagation = Propagation.REQUIRES_NEW)是无效的,在Spring中是使用代理的方式实现事务,发生自身调用的时候,没有经过Spring的代理,自然事务失效.
不支持事务
@Service
public class UserServiceImpl implements UserService {
@Transactional(propagation = Propagation.NOT_SUPPORTED)
public void update(User user) {
//do some action
}
}
@Transactional(propagation = Propagation.NOT_SUPPORTED)表示如果当前存在事务就挂起,以没有事务的方式运行,主动不支持事务了,那么再怎么操作也是白搭. 此处贴下Spring的传播行为:
/**
* Support a current transaction, create a new one if none exists.
* Analogous to EJB transaction attribute of the same name.
* <p>This is the default setting of a transaction annotation.
*/
REQUIRED(TransactionDefinition.PROPAGATION_REQUIRED),
/**
* Support a current transaction, execute non-transactionally if none exists.
* Analogous to EJB transaction attribute of the same name.
* <p>Note: For transaction managers with transaction synchronization,
* PROPAGATION_SUPPORTS is slightly different from no transaction at all,
* as it defines a transaction scope that synchronization will apply for.
* As a consequence, the same resources (JDBC Connection, Hibernate Session, etc)
* will be shared for the entire specified scope. Note that this depends on
* the actual synchronization configuration of the transaction manager.
* @see org.springframework.transaction.support.AbstractPlatformTransactionManager#setTransactionSynchronization
*/
SUPPORTS(TransactionDefinition.PROPAGATION_SUPPORTS),
/**
* Support a current transaction, throw an exception if none exists.
* Analogous to EJB transaction attribute of the same name.
*/
MANDATORY(TransactionDefinition.PROPAGATION_MANDATORY),
/**
* Create a new transaction, and suspend the current transaction if one exists.
* Analogous to the EJB transaction attribute of the same name.
* <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
* on all transaction managers. This in particular applies to
* {@link org.springframework.transaction.jta.JtaTransactionManager},
* which requires the {@code javax.transaction.TransactionManager} to be
* made available to it (which is server-specific in standard Java EE).
* @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
*/
REQUIRES_NEW(TransactionDefinition.PROPAGATION_REQUIRES_NEW),
/**
* Execute non-transactionally, suspend the current transaction if one exists.
* Analogous to EJB transaction attribute of the same name.
* <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
* on all transaction managers. This in particular applies to
* {@link org.springframework.transaction.jta.JtaTransactionManager},
* which requires the {@code javax.transaction.TransactionManager} to be
* made available to it (which is server-specific in standard Java EE).
* @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
*/
NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED),
/**
* Execute non-transactionally, throw an exception if a transaction exists.
* Analogous to EJB transaction attribute of the same name.
*/
NEVER(TransactionDefinition.PROPAGATION_NEVER),
/**
* Execute within a nested transaction if a current transaction exists,
* behave like PROPAGATION_REQUIRED else. There is no analogous feature in EJB.
* <p>Note: Actual creation of a nested transaction will only work on specific
* transaction managers. Out of the box, this only applies to the JDBC
* DataSourceTransactionManager when working on a JDBC 3.0 driver.
* Some JTA providers might support nested transactions as well.
* @see org.springframework.jdbc.datasource.DataSourceTransactionManager
*/
NESTED(TransactionDefinition.PROPAGATION_NESTED);
异常被catch
@Service
public class UserServiceImpl implements UserService {
@Transactional
public void update(User user) {
try{
}catch(Exception e){
log.error(e.getMessage(),e);
}
}
}
触发回滚的操作是被接收到异常,一般我们会在@Transactional后面加上rollbackFor或者noRollbackForClassName来指明触发回滚的异常,但是如果在代码中给catch了异常,那么对于Spring代理来说就这个方法从头到尾都没有问题,自然不会触发回滚.
异常类型错误
@Service
public class UserServiceImpl implements UserService {
@Transactional
public void update(User user) {
try{
}catch(Exception e){
log.error(e.getMessage(),e);
throw new Exception(e.getMessage());
}
}
}
以上方式throw new Exception(e.getMessage());事务也是无效的,主要原因是事务回滚的条件是throw 运行时异常(RunTimeException).如果需要其他异常也回滚,需要在@Transactional后面加上rollbackFor或者noRollbackForClassName来指明触发回滚的异常.
没有被Spring管理
不在Spring环境下,自然不受Spring的管理,事务管理器也当然失去了作用.
没有配置TransactionManager
需要对当前数据源配置事务管理器,尤其是在多数据源的情况下.
