使用 Spring 整合 Hibernate, 在懒加载的情况下, 有时候需要在 JSP/View 层显示数据, 这时候就要用到Spring内置的: OpenSessionInViewFilter, 一般来说配置如下(web.xml):
<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
</filter-class>
<init-param>
<param-name>singleSession</param-name>
<param-value>true</param-value>
</init-param><!-- 和 spring 中的sesssionfactory ID 一致 -->
</filter>
<filter-mapping><filter-name>hibernateFilter</filter-name><url-pattern>*.do</url-pattern><!-- *.jsp, *.do--></filter-mapping>
不过, 这时候又会导致更新数据时抛出如下异常:
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.
这时候再去网上找解决方案, 会有人说: 把参数 singleSession改为false, 就行了. 不过, 改完后, 估计不久就会遇到另一个郁闷的异常:
org.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions
这下完了, 两个方案都不行, 到底怎么办? 还好, 在http://xuliangyong.javaeye.com/blog/144818的主页上, 给了一个方案, 就是改写 OpenSessionInViewFilter 的代码, 非常感谢, 下面给出的就是最终方案:
web.xml
<
filter-name
>hibernateFilter</filter-name>
<
filter-class
> org.springframework.orm.hibernate3.support.OurOpenSessionInViewFilter </filter-class>
OurOpenSessionInViewFilter.java 代码:
package org.springframework.orm.hibernate3.support;
import org.hibernate.*;
/** * 单session模式下, 默认会发生无法提交的错误: * 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. * 需要设置FlushMode并刷新session. * 参考: http://xuliangyong.javaeye.com/blog/144818 * @author 刘长炯 */publicclass OurOpenSessionInViewFilter extends OpenSessionInViewFilter {
public OurOpenSessionInViewFilter() {
super.setFlushMode(FlushMode.AUTO);
}
protectedvoid closeSession(Session session, SessionFactory sessionFactory) {
session.flush();
try {
session.getTransaction().commit();
} catch (HibernateException e) {
// TODO Auto-generated catch block//e.printStackTrace();
}
super.closeSession(session, sessionFactory);
}
}
如果各位有更好的解决方案, 欢迎讨论哦!!!
题外话:
感觉 Spring + Hibernate 的健壮性还是不够啊! 容易抛异常, 这是事实, 也许这是开源软件的通病吧.