Hibernate has been used recently, encountered in the implementation of inquiry个"Session is closed!" Troublesome, is as follows:



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)





At the beginning of my abstract Dao ri are written so: 



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;
	}



Dao examples, however, are: 

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;
	}




In my search for a long time-line information, the solution is still not allowed. Suddenly switch to List rather than Iterator, then slightly changed under the two sections of code: 

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;
	}




Unexpectedly, only one such change was not wrong! Puzzled ... ...