OpenSessionInViewFilter更新问题

 

SpringHibernateDAOXMLORM

在项目中配置OpenSessionInViewFilter后，首先会出现的问题：

Java代码

1. org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not allowed in read-only mode (FlushMode.NEVER/MANUAL): Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction definition.

org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not allowed in read-only mode (FlushMode.NEVER/MANUAL): Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction definition.

这个是因为OpenSessionInViewFilter在getSession的时候,会把获取回来的session的flushMode 设为FlushMode.NEVER。然后把该sessionFactory绑定到TransactionSynchronizationManager，使request的整个过程都使用同一个session。
FlushMode.NEVER模式不具备写操作，可以把session配置为FlushMode.AUTO，如在web.xml中配置：

Xml代码

1. <filter>
2. <filter-name>OpenSessionInView</filter-name>
3. <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
4. <init-param>
5. <param-name>flushMode</param-name>
6. <param-value>AUTO</param-value>
7. </init-param>
8. </filter>

<filter>  	<filter-name>OpenSessionInView</filter-name>  	<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>  		<init-param>          	<param-name>flushMode</param-name>          	<param-value>AUTO</param-value>      	</init-param>  </filter>

其次，会遇到的另外一个问题是页面更新操作，因为这个流程是：首先查询取得数据库中的记录，修改客户端改变的属性，更新这个实体类。这是通过以上配置OpenSessionInViewFilter，在session更新实体类之前，session已经存在一个实体类，与客户端传过来的需要修改的实体类会发生冲突，以致更新失败。这个可以通过配置singleSession=false解决。也可以通过重写OpenSessionInViewFilter类的getSession及closeSession方法实现，如：

Java代码

1. public class MyOpenSessionInViewFilter extends OpenSessionInViewFilter{
3. @Override
4. protected void closeSession(Session session, SessionFactory sessionFactory) {
5. session.flush();
6. session.getTransaction().commit();
7. super.closeSession(session, sessionFactory);
8. }
10. @Override
11. protected Session getSession(SessionFactory sessionFactory)
12. throws DataAccessResourceFailureException {
13. Session session = SessionFactoryUtils.getSession(sessionFactory, true);
14. session.beginTransaction();
15. FlushMode flushMode = getFlushMode();
16. if (flushMode != null) {
17. this.setFlushMode(FlushMode.AUTO);
18. }
19. return session;
20. }
22. }