Hibernate课程 初探一对多映射2-7 测试-修改和删除学生信息

package com.ddwei.entity;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.ddwei.util.HibernateUtil;

/**
 * 建立关联关系后，
 * 可以方便的从一个导航对象，关联到另一个导航对象！
 * 注意关联方向：一对多
 * @author weijingli
 *
 */
public class Test {

    public static void main(String[] args) {
//        add();
//        show();
//        updateGrade();
        deleteStu();
    }

    //增加班级学生信息
    public static void add(){

        Grade g = new Grade("java一班","java一班是一个好班");
        Student stu1 = new Student("秦皇","男");
        Student stu2 = new Student("汉武","男");
        Student stu3 = new Student("唐宗","男");
        g.getStudents().add(stu1);
        g.getStudents().add(stu2);
        g.getStudents().add(stu3);
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();
        session.save(g);
        session.save(stu1);
        session.save(stu2);
        session.save(stu3);
        tx.commit();
        HibernateUtil.closeSession(session);
    }

    //查询班级学生信息
    public static void show(){

        Session session1 = HibernateUtil.getSession();
        Grade grade1 = (Grade) session1.get(Grade.class, 1);//得到java1班
        System.out.println("班级名称为："+grade1.getGname());
        Set<Student> students = grade1.getStudents();
        for(Student stu:students){
            System.out.println("学生姓名为："+stu.getSname());
        }
        HibernateUtil.closeSession(session1);
    }

    //修改学生所在班级信息
    public static void updateGrade(){

        Grade grade2 = new Grade("java二班","java二班介绍");
        Session session2 = HibernateUtil.getSession();
        Transaction tx2 = session2.beginTransaction();
        Student student1 = (Student) session2.get(Student.class, 1);
        grade2.getStudents().add(student1);//java二班添加学号为1的学生
        session2.save(grade2);
        tx2.commit();
        HibernateUtil.closeSession(session2);
    } 

    //删除学生信息
    public static void deleteStu(){
        Session session2 = HibernateUtil.getSession();
        Transaction tx2 = session2.beginTransaction();
        Student stu2 = (Student)session2.get(Student.class, 3);
        session2.delete(stu2);
        tx2.commit();
        HibernateUtil.closeSession(session2);
    }

}