Hibernate疑惑

 

最近又用到Hibernate了，在执行查询时碰到个“Session is closed！”麻烦，如下：

 

org.hibernate.SessionException: Session is closed!

at org.hibernate.impl.AbstractSessionImpl.errorIfClosed(AbstractSessionImpl.java:72)

at org.hibernate.impl.SessionImpl.getPersistenceContext(SessionImpl.java:1850)

at org.hibernate.type.ManyToOneType.scheduleBatchLoadIfNeeded(ManyToOneType.java:142)

at org.hibernate.type.ManyToOneType.hydrate(ManyToOneType.java:128)

at org.hibernate.type.EntityType.nullSafeGet(EntityType.java:227)

at org.hibernate.impl.IteratorImpl.next(IteratorImpl.java:135)

at database.ValidationDAO.find(ValidationDAO.java:35)

at test.testHibe.main(testHibe.java:16)

 

 

开始在我的抽象Dao里是这么写的：

 

protected Iterator find(Class clazz,String user){
		Iterator it = null;
		try {
			startOperation();
			Query q=session.createQuery("from "+clazz.getName()+" v where v.user = :user");
			q.setParameter("user", user);
			it=q.iterate();
			tx.commit();
		} catch (HibernateException e) {
			handleException(e);
		} finally {
			HibernateFactory.close(session);
		}
		return it;
	}

 

实例Dao中则是：

public Validation find(String user) {
		try {
			Iterator it = this.find(Validation.class, user,null);
			if(it.hasNext())
			return (Validation) it.next();

		} catch (Exception e) {
		e.printStackTrace();
		}
		return null;
	}

 

在我搜了半天网上资料后，依旧不得解。突然想到改用List而不是Iterator，于是稍微改了下两段代码：

protected List find(Class clazz,String user){
		List list = null;
		try {
			startOperation();
			Query q=session.createQuery("from "+clazz.getName()+" v where v.user = :user");
			q.setParameter("user", user);
			list=q.list();
			tx.commit();
		} catch (HibernateException e) {
			handleException(e);
		} finally {
			HibernateFactory.close(session);
		}
		return list;
	}

 

public Validation find(String user) {
		try {
			List list=find(Validation.class,user);
			Iterator it=list.iterator();
			if(it.hasNext()){				
				return (Validation)it.next();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

 

没想到，仅仅这样一改竟然就没错误了！百思不得其解……