open Session in view出现错误的解决方法Write operations are not allowed in read-only mode (FlushMode.NEVER) -

 

使用Spring提供的Open Session In View而引起Write operations are not allowed in read-only mode (FlushMode.NEVER) 错误解决：
在没有使用Spring提供的Open Session In View情况下，因需要在service(or Dao)层里把session关闭，所以lazy loading 为true的话，要在应用层内把关系集合都初始化，如 company.getEmployees()，否则Hibernate抛session already closed Exception; Open Session In View提供了一种简便的方法，较好地解决了lazy loading问题.
它有两种配置方式OpenSessionInViewInterceptor和OpenSessionInViewFilter(具体参看SpringSide)，功能相同，只是一个在web.xml配置，另一个在application.xml配置而已。Open Session In View在request把session绑定到当前thread期间一直保持hibernate session在open状态，使session在request的整个期间都可以使用，如在View层里PO也可以lazy loading数据，如 ${ company.employees }。当View 层逻辑完成后，才会通过Filter的doFilter方法或Interceptor的postHandle方法自动关闭session。
OpenSessionInViewInterceptor 配置
<beans>
<bean name="openSessionInViewInterceptor" class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor">
<property name="sessionFactory" ref="sessionFactory"/></property>
</bean>
<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
<property name="interceptors">
<list><ref bean="openSessionInViewInterceptor"/></list>
</property>
<property name="mappings">

</property>
</bean>
</beans>
OpenSessionInViewFilter配置
<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
<!-- singleSession默认为true,若设为false则等于没用OpenSessionInView -->
<init-param>
<param-name>singleSession</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>hibernateFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
很多人在使用OpenSessionInView过程中提及一个错误：
org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not allowed in read-only mode (FlushMode.NEVER) - turn your Session into FlushMode.AUTO or remove 'readOnly' marker from transaction definition
看看OpenSessionInViewFilter里的几个方法
protected void doFilterInternal(HttpServletRequest request,
HttpServletResponse response,FilterChain filterChain)
throws ServletException, IOException {
SessionFactory sessionFactory = lookupSessionFactory();
logger.debug("Opening Hibernate Session in OpenSessionInViewFilter");
Session session = getSession(sessionFactory);
TransactionSynchronizationManager.bindResource(
sessionFactory, new SessionHolder(session));
try {
filterChain.doFilter(request, response);
}
finally {
TransactionSynchronizationManager.unbindResource(sessionFactory);
logger.debug("Closing Hibernate Session in OpenSessionInViewFilter");
closeSession(session, sessionFactory);
}
}

protected Session getSession(SessionFactory sessionFactory)
throws DataAccessResourceFailureException {
Session session = SessionFactoryUtils.getSession(sessionFactory, true);
session.setFlushMode(FlushMode.NEVER);
return session;
}

protected void closeSession(Session session, SessionFactory sessionFactory)
throws CleanupFailureDataAccessException {
SessionFactoryUtils.closeSessionIfNecessary(session, sessionFactory);
}