hibernate中session，HQL，持久化，一对多，多对一

Posted 2020-08-19 HRZJ

package com.hanqi.test;
import java.util.Date;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.hanqi.entity.Course;
import com.hanqi.entity.Teacher;
import com.hanqi.entity.User;

public class Test01 {
private SessionFactory sf=null;
private Session se=null;
private Transaction ts;

//在测试用例执行之前自动执行的方法
//一般用来初始化的公用对象
//前置方法
@Before
public void init()
{
            //1获取配置文件
            Configuration cfg=new Configuration().configure();
            
            
            //2注册配置
            ServiceRegistry sr=new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build();
            
            
            //3获取SessionFactory(相当于JDBC)
             sf =cfg.buildSessionFactory(sr);
            
            System.out.println(sf);
            
            //4产生Session
             se=sf.openSession();
            
            //5启动事务
             ts=se.beginTransaction();
}

//后置方法
//一般用来释放资源
@After
public void destroy()
{
            //7提交事务
    
            ts.commit();
            //8释放资源
            se.close();
            sf.close();
    
}

//测试Hibernate连接数据库


@Test
public void test() 
{
    //1获取配置文件
    Configuration cfg=new Configuration().configure();
    
    
    //2注册配置
    ServiceRegistry sr=new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build();
    
    
    //3获取SessionFactory(相当于JDBC)
    SessionFactory sf =cfg.buildSessionFactory(sr);
    
    System.out.println(sf);
    
    //4产生Session
    Session se=sf.openSession();
    
    //5启动事务
     ts=se.beginTransaction();
    
    //6操作事务
    //添加数据
     //实例化的新对象处于临时状态
    User u1=new User();
    u1.setBirthday(new Date());
    u1.setMoney(2000);
    u1.setPassword("123456");
    u1.setUserName("测试一");
    
    //保存数据
    //通过save方法把对象从临时状态转成持久化状态
    se.save(u1);
    System.out.println(u1);
    
}
//测试查询方法
@Test
public void test1()
{
    //查询数据
    //提供两个参数：
    //1需要返回哪一个持久化类的实例
    //2实例的标识(数据的主键值)
    //通过Session的get方法获得的对象处于持久化状态
    User u2=(User)se.get(User.class,3);
    
    u2.setUserName("修改的");
    
    System.out.println(u2);
    
    //删除
    se.delete(u2);//使持久化对象进入删除状态
}
@Test
public void test2()
{
    User u1=(User)se.get(User.class, 4);
    
    System.out.println(u1);
    
    User u2=(User)se.get(User.class, 4);//立即加载数据
    System.out.println(u2);
}
@Test
public void test3()
{
    User u1=(User)se.load(User.class, 4);//延时加载  懒加载
    System.out.println("dsad");
    System.out.println(u1);//当使用时才加载
}

//测试游离状态


@Test
public void test4()
{
    //得到持久化状态的对象
    User u1=(User)se.get(User.class,4);
    System.out.println("u1="+u1);
    //关闭session 
    se.close();
    
    //使u1进入游离状态
    u1.setUserName("测试游离");
    //把OID置成null
    u1.setUserID(null);
    
    
    //重新创建session
    se=sf.openSession();
    //重新开启事务
    ts=se.beginTransaction();
    
    
    se.saveOrUpdate(u1);
    System.out.println(u1);     
}
//测试HQL
@Test
public void test5()
{
    //使用HQL
    //1创建Query对象
    Query qu=se.createQuery("from User where userID >? and "
            + "userName like ‘测试%‘ order by userID");
    
    //设置占位符
    qu.setInteger(0, 10);
            
    
    //执行查询
    List<User> lu=qu.list();
    
    //方法链调用
    //lu=se.createQuery("from User where userID >?").setInteger(0, 10).list();
    
    
    for(User e:lu)
    {
        System.out.println(e);
    }
}
//测试分页
@Test
public void test6()
{
    //设置开始行号:页码=2
    //(页码-1)*每页行数
    List<User> lu=se.createQuery("from User order by userID")
            .setMaxResults(5)
            .setFirstResult(5)
            .list();


    for(User e:lu)
    {
        System.out.println(e);
    }

}
//分组查询
@Test
public void test7()
{
    List<Object>lo=se.createQuery("select userName from User group by userName").list();

    for(Object o:lo)
    {
    System.out.println(o);
    }

}
//测试投影查询
@Test
public void test8()
{
    List<Object[]>lo=se.createQuery("select userID,userName from User").list();
    
    for(Object[] o:lo)
    {
        System.out.println(o[0]+" "+o[1]);
    }
    System.out.println("dasdasadfa");
    //返回持久化对象的集合
    List<User> lu=se.createQuery("select new User(userID,userName) from User").list();

    for(User u:lu)
    {
        System.out.println(u);
        
    }

}
//测试多对一
@Test
public void test10()
{
    Course cs=(Course)se.get(Course.class,"9-888");
            System.out.println(cs);
}
//测试一对多
@Test
public void test11()
{
    Teacher  tc=(Teacher)se.get(Teacher.class,"831");
    System.out.println(tc);
}

}