Spring Hibernate整合难点

public User saveAndFindAll(){
    User user = new User();
    user.setUserName("chenglong");
    user.setNickName("huanhuan");
    user.setLoginTimes(5);
    user.setPhone("13261165539");
    user.setRegTime(new Date());

    userDao.save(user);   //插入	
    return userDao.findAll(User.class);//查询
}

    如果没有配置事务，日志是这样：（注意加粗处session的开关以及session.flush()的时机）

2010-11-11 14:29:59,855 DEBUG [org.springframework.orm.hibernate3.SessionFactoryUtils] - Opening Hibernate Session
Hibernate: insert into User (userName, nickName, regTime, loginTimes, phone, lastLogin) values (?, ?, ?, ?, ?, ?)
2010-11-11 14:29:59,925 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Eagerly flushing Hibernate session
2010-11-11 14:29:59,930 DEBUG [org.springframework.orm.hibernate3.SessionFactoryUtils] - Closing Hibernate Session
2010-11-11 14:29:59,930 DEBUG [org.springframework.orm.hibernate3.SessionFactoryUtils] - Opening Hibernate Session
Hibernate: select this_.userId as userId0_0_, this_.userName as userName0_0_, this_.nickName as nickName0_0_, this_.regTime as regTime0_0_, this_.loginTimes as loginTimes0_0_, this_.phone as phone0_0_, this_.lastLogin as lastLogin0_0_ from User this_
2010-11-11 14:29:59,955 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Eagerly flushing Hibernate session
Hibernate: update User set userName=?, nickName=?, regTime=?, loginTimes=?, phone=?, lastLogin=? where userId=?
Hibernate: update User set userName=?, nickName=?, regTime=?, loginTimes=?, phone=?, lastLogin=? where userId=?
2010-11-11 14:29:59,980 DEBUG [org.springframework.orm.hibernate3.SessionFactoryUtils] - Closing Hibernate Session

如果配置了事务，日志是这样：（注意加粗处session的处理,以及事务的处理）
2010-11-11 14:19:01,645 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Initializing transaction synchronization
2010-11-11 14:19:01,645 DEBUG [org.springframework.transaction.interceptor.TransactionInterceptor] -Getting transaction for
[com.supben.service.UserService.saveAndFindAll]
2010-11-11 14:19:01,650 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] bound to thread [main]
2010-11-11 14:19:01,650 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] bound to thread [main]
2010-11-11 14:19:01,650 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Found thread-bound Session for HibernateTemplate
Hibernate: insert into User (userName, nickName, regTime, loginTimes, phone, lastLogin) values (?, ?, ?, ?, ?, ?)
2010-11-11 14:19:01,680 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Not closing pre-bound Hibernate Session after HibernateTemplate
2010-11-11 14:19:01,685 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] bound to thread [main]
2010-11-11 14:19:01,685 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] bound to thread [main]
2010-11-11 14:19:01,685 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Found thread-bound Session for HibernateTemplate
2010-11-11 14:19:01,690 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] bound to thread [main]
Hibernate: select this_.userId as userId0_0_, this_.userName as userName0_0_, this_.nickName as nickName0_0_, this_.regTime as regTime0_0_, this_.loginTimes as loginTimes0_0_, this_.phone as phone0_0_, this_.lastLogin as lastLogin0_0_ from User this_
2010-11-11 14:19:01,715 DEBUG [org.springframework.orm.hibernate3.HibernateTemplate] - Not closing pre-bound Hibernate Session after HibernateTemplate
2010-11-11 14:19:01,715 DEBUG [org.springframework.transaction.interceptor.TransactionInterceptor] - Completing transaction for [com.supben.service.UserService.saveAndFindAll]
2010-11-11 14:19:01,715 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Triggering beforeCommit synchronization
2010-11-11 14:19:01,715 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Triggering beforeCompletion synchronization
2010-11-11 14:19:01,715 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Initiating transaction commit
2010-11-11 14:19:01,715 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Committing Hibernate transaction on Session [org.hibernate.impl.SessionImpl@b86944]
Hibernate: update User set userName=?, nickName=?, regTime=?, loginTimes=?, phone=?, lastLogin=? where userId=?
2010-11-11 14:19:01,745 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Triggering afterCommit synchronization
2010-11-11 14:19:01,745 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Triggering afterCompletion synchronization
2010-11-11 14:19:01,750 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Clearing transaction synchronization
2010-11-11 14:19:01,750 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Removed value [org.springframework.orm.hibernate3.SessionHolder@89e2f1] for key [org.hibernate.impl.SessionFactoryImpl@68cd79] from thread [main]
2010-11-11 14:19:01,750 DEBUG [org.springframework.transaction.support.TransactionSynchronizationManager] - Removed value [org.springframework.jdbc.datasource.ConnectionHolder@1117a20] for key [org.apache.commons.dbcp.BasicDataSource@1192059] from thread [main]
2010-11-11 14:19:01,750 DEBUG [org.springframework.orm.hibernate3.HibernateTransactionManager] - Closing Hibernate Session [org.hibernate.impl.SessionImpl@b86944] after transaction
2010-11-11 14:19:01,750 DEBUG [org.springframework.orm.hibernate3.SessionFactoryUtils] - Closing Hibernate Session

    很容易看到：如果没有配置事务，hibernateDaoSupport采用的是传统的open-per-operation模式。即：打开一个session----执行添加----从内存flush到数据库中----
关闭session----打开一个session----执行查询----flush到数据库中(2条update操作是flush的一部分...)----关闭session

    如果配置了，操作过程则是：打开事务----开启一个session并绑定到当前线程中，执行添加----检查是否要关闭session（否）----拿到当前线程的session----执行查询----检查session是否要关闭（是）----提交事务----关闭session。

   显然，后者的session管理更科学了，看起来save之后没有调用flush,好像保证不了save之后数据的正确性。其实不是！因为他们是同一个session中，所以仍然不影响结果！




    结论：无论数据库支不支持事务，或者说业务需不需要。都用aop的方式对service方法配上事务管理！

    这时候，spring会完全负责hibernateDaoSupport中的getSession(),getCurrentSession()以及getHibernateTemplate()三个方法中的session开关。即spring能保证在一个service方法中中只出现一个 hibernate session。在第一次发sql前打开，在最后一次发sql后关闭。

     严禁用SessionFactory的openSession()自己获取一个session。这样得到的session无法控制的。

    至于openSessionInView。整个request--response的生命周期，一直用一个session，好像没什么很强的必要性，而且带来的负面问题极多，所以不建议使用。



附上：事务的声明式配置方法

<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory">
      <ref local="sessionFactory" />
    </property>
  </bean>

  <tx:advice id="txAdvice" transaction-manager="transactionManager">
    <tx:attributes>
      <tx:method name="save*" />
      <tx:method name="update*" />
      <tx:method name="remove*" />
      <tx:method name="*" read-only="true" />
    </tx:attributes>
  </tx:advice>

  <aop:config>
    <aop:pointcut id="serviceMethod" expression="execution(* com.supben.service.impl.*.*(..))"/>
    <aop:advisor advice-ref="txAdvice" pointcut-ref="serviceMethod" />
  </aop:config>

评论

1 楼 beifengcast2 2014-09-16  

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