欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

Hibernate双向多对一实战

程序员文章站 2022-07-11 20:23:09
...
一 双向多对一生活举例

Hibernate双向多对一实战
            
    
    博客分类: Hibernate Hibernate双向多对一 
 
 
二 Grade.hbm.xml配置一对多关联关系
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
<hibernate-mapping>
        <class name="com.imooc.entity.Grade" table="grade">
                <id name="gid" column="gid" type="java.lang.Integer">
                        <generator class="increment"></generator>
                </id>
                <property name="gname" type="java.lang.String">
                        <column name="gname" length="20" not-null="true"></column>
                </property>
                <property name="gdesc">
                        <column name="gdesc"></column>
                </property>
                <!-- 配置一对多关联关系 -->
                <set name="students" table="student">
                        <key column="gid"></key>
                        <one-to-many class="com.imooc.entity.Student"/>
                </set>
        </class>
</hibernate-mapping>
 
三 Student.hbm.xml配置多对一关联关系
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
<hibernate-mapping>
        <class name="com.imooc.entity.Student" table="student">
                <id name="sid" column="sid" type="java.lang.Integer">
                        <generator class="increment"></generator>
                </id>
                <property name="sname" type="java.lang.String">
                        <column name="sname" length="20" not-null="true"></column>
                </property>
                <property name="sex">
                        <column name="sex"></column>
                </property>
                <!-- 配置多对一关联关系 -->
                <many-to-one name="grade" class="com.imooc.entity.Grade" column="gid" ></many-to-one>
                
        </class>
</hibernate-mapping>
 
四 测试代码
package com.imooc.test;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.imooc.entity.Grade;
import com.imooc.entity.Student;
import com.imooc.util.HibernateUtil;
/*
* 单向多对一(学生--->班级)
*/
public class Test02 {
    public static void main(String[] args) {
        save();
    }
    
    //保存
    public static void save(){
        Grade g=new Grade("Java一班","Java软件开发一班");
        Student stu1=new Student("慕女神", "女");
        Student stu2=new Student("小慕慕", "男");
        
        //设置关联关系
        g.getStudents().add(stu1);
        g.getStudents().add(stu2);
        stu1.setGrade(g);
        stu2.setGrade(g);
        
        Session session=HibernateUtil.getSession();
        Transaction tx=session.beginTransaction();
        session.save(g);
        session.save(stu1);
        session.save(stu2);
        tx.commit();
        HibernateUtil.closeSession(session);
    }
}
 
五 测试结果
Hibernate: select max(gid) from grade
Hibernate: select max(sid) from student
Hibernate: insert into grade (gname, gdesc, gid) values (?, ?, ?)
Hibernate: insert into student (sname, sex, gid, sid) values (?, ?, ?, ?)
Hibernate: insert into student (sname, sex, gid, sid) values (?, ?, ?, ?)
Hibernate: update student set gid=? where sid=?
Hibernate: update student set gid=? where sid=?
从后台输出来看,多余了两条update语句。

 


Hibernate双向多对一实战
            
    
    博客分类: Hibernate Hibernate双向多对一 
 
  • Hibernate双向多对一实战
            
    
    博客分类: Hibernate Hibernate双向多对一 
  • 大小: 397.5 KB
  • Hibernate双向多对一实战
            
    
    博客分类: Hibernate Hibernate双向多对一 
  • 大小: 19.5 KB