java uniqueresult_Hibernate之Query接口的uniqueResult()方法详解

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

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();

}