为什么总是出现“空指针异常”????!!!!
Hibernate+Tomcat+MySQL开发,信息说我这段代码有问题,突然间的
public class UserBiz implements Serializable
{
// 登陆功能,用于判断登陆是否成功
public User login( String userName , String password )
{
User user = null ;
Session session = null ;
Transaction tx = null ;
try
{
session = HbnUtil.getSession() ;
tx = session.beginTransaction() ;
Query query = session.createQuery( "from User as u where u.userName=:userName and u.password=:password" ).setString( "userName" , userName )
.setString( "password" , password ) ;
List list = query.list() ;
if ( list.size() != 0 )
{
Iterator iterator = list.iterator() ;
while ( iterator.hasNext() )
{
user = ( User ) iterator.next() ;
}
}
tx.commit() ;
} catch ( HibernateException e )
{
tx.rollback() ;
e.printStackTrace();
}
finally
{
// 访问数据库结束后必须关闭这个Session,以释放资源,这是必须的!!!!
session.close() ;(说这一行有错误,空指针异常)
}
return user ;
}
}