Hibernate之Query接口的uniqueResult()方法详解编程语言

如果查询返回多个值用list()方法

public void testQuery(){ 
		Configuration config = new Configuration().configure(); 
		SessionFactory factory = config.buildSessionFactory(); //创建SessionFactory 
		Session session = factory.openSession();        //创建Session 
		session.beginTransaction();                     //开始事务 
		 
		Query query = session.createQuery("from Student"); 
		List list = query.list();  // 用list方法返回多个值 
		//List list = session.createQuery("from Student").list(); 
		for(int i=0;i<list.size();i++){ 
			Student student = (Student)list.get(i); 
			System.out.print(student.getId()+" "); 
			System.out.print(student.getName()+" "); 
			System.out.print(student.getSex()+" "); 
			System.out.print(student.getBirthday()); 
			System.out.println(); 
		}		 
		 
		session.getTransaction().commit();         //提交事务  
		session.close();                           //关闭Session 
	} 
 

当确定返回的实例只有一个或者null时 用uniqueResult()方法

public void testGet(){ 
		Configuration config = new Configuration().configure(); 
		SessionFactory factory = config.buildSessionFactory(); 
		Session session = factory.openSession(); 
		session.beginTransaction(); 
		 
		Query query = session.createQuery("from Student s where s.id=?"); 
		query.setString(0, "2"); 
		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 
		//Student student = (Student)session.createQuery("from Student s where s.id=?").setString(0,"5").uniqueResult(); 
		 
		System.out.println(student.getName()); 
		System.out.println(student.getBirthday()); 
		 
	 
		session.getTransaction().commit(); 
		session.close(); 
	}