org.hibernate.SessionException: Session is closed!第一次可以运行，第二次就报错

web.xml配置如下：

<!-- 过滤器，使session在页面加载完后关闭 -->

	<filter>

		<filter-name>HibernateSessionFilter</filter-name>

		<filter-class>com.util.HibernateSessionFilter</filter-class>

	</filter>

	<filter-mapping>

		<filter-name>HibernateSessionFilter</filter-name>

		<url-pattern>/*</url-pattern>

	</filter-mapping>



HibernateSessionFilter类配置如下：

public class HibernateSessionFilter implements Filter {	

	private Transaction tx ;

	private SessionFactory sessionFactory;

	public void destroy() {

		sessionFactory.close();

	}

	public void doFilter(ServletRequest request, ServletResponse response,

			FilterChain chain) throws IOException, ServletException {

		//在用户发出请求的时候获得session对象

		try {

			Session session = sessionFactory.getCurrentSession();

			tx = session.beginTransaction();

			chain.doFilter(request, response);

			tx.commit();

		} catch (HibernateException e) {

			// TODO 自动生成 catch 块

			e.printStackTrace();

			if (tx.isActive()) { //如果事务存活,发生违例

				tx.rollback();

			}

		}

	}

	public void init(FilterConfig arg0) throws ServletException {

		//初始化

		sessionFactory = HibernateSessionFactoryUtil.getSessionFactory();

	}

}

servlet中调用：

	public void list(HttpServletRequest request, HttpServletResponse response)

		throws ServletException, IOException {

		List<GuestBook> list = dao.findAllOrderById();

		request.setAttribute("admin.list", list);

		request.getRequestDispatcher("/admin/secure/list.jsp").forward(request, response);

	}

GuestBookDaoHibernate 类：

public class GuestBookDaoHibernate extends GenericDaoHibernate<GuestBook, Integer> implements GuestBookDao {



	private Session session = HibernateSessionFactoryUtil.getSessionFactory().getCurrentSession();

	public List<GuestBook> findAllOrderById() {

		Query query = session.createQuery("from GuestBook order by id desc");

		return query.list();

	}

}

通用的类：

public class GenericDaoHibernate<T,PK extends Serializable> implements GenericDao<T,PK> {

	private Session session = HibernateSessionFactoryUtil.getSessionFactory().getCurrentSession();

	private Class<T> clazz;

	public GenericDaoHibernate(){

		//获取持久化对象clazz的真正类型

		//通过反射 获取反射当中擦拭法获取泛型的真正类型

		clazz = (Class<T>)((ParameterizedType)getClass().getGenericSuperclass())

				.getActualTypeArguments()[0];

	}

	public void delete(T entity) {

		session.delete(entity);

	}

	public List findAll() {

		Query query = session.createQuery("from " + clazz.getName());

		return query.list();

	}

	public T findById(PK id) {

		return (T)session.get(clazz, id);

	}

	public T save(T entity) {

		session.save(entity);

		return entity;

	}

	public void update(T entity) {

		session.update(entity);

	}

}

接口：

public interface GuestBookDao extends GenericDao<GuestBook, Integer>{	

	public List<GuestBook> findAllOrderById();	

}