Hibernate之Query接口的uniqueResult()方法

如果查询返回多个值用list()方法

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1. public void testQuery(){  
2.         Configuration config = new Configuration().configure();  
3.         SessionFactory factory = config.buildSessionFactory(); //创建SessionFactory  
4.         Session session = factory.openSession();        //创建Session  
5.         session.beginTransaction();                     //开始事务  
6.           
7.         Query query = session.createQuery("from Student");  
8.         List list = query.list();  // 用list方法返回多个值  
9.         //List list = session.createQuery("from Student").list();  
10.         for(int i=0;i<list.size();i++){  
11.             Student student = (Student)list.get(i);  
12.             System.out.print(student.getId()+" ");  
13.             System.out.print(student.getName()+" ");  
14.             System.out.print(student.getSex()+" ");  
15.             System.out.print(student.getBirthday());  
16.             System.out.println();  
17.         }         
18.           
19.         session.getTransaction().commit();         //提交事务   
20.         session.close();                           //关闭Session  
21.     }  

当确定返回的实例只有一个或者null时 用uniqueResult()方法

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1. public void testGet(){  
2.         Configuration config = new Configuration().configure();  
3.         SessionFactory factory = config.buildSessionFactory();  
4.         Session session = factory.openSession();  
5.         session.beginTransaction();  
6.           
7.         Query query = session.createQuery("from Student s where s.id=?");  
8.         query.setString(0, "2");  
9.         Student student = (Student)query.uniqueResult();  //当确定返回的实例只有一个或者null时 用uniqueResult()方法  
10.         //Student student = (Student)session.createQuery("from Student s where s.id=?").setString(0,"5").uniqueResult();  
11.           
12.         System.out.println(student.getName());  
13.         System.out.println(student.getBirthday());  
14.           
15.       
16.         session.getTransaction().commit();  
17.         session.close();  
18.     }