Hibernate学习（一）---【多对一】

Hibernate学习（一）---【多对一】

User和Group，关系多对一。
注意：cascade是级联。也就是说对主表保存、更新、删除都会级联的操作附表。
User.java

1  public   class  User {
          p rivate  String id;
3       private  String name;
4       private   int  age;
5       private  Group group;
6      get(),set()省略
7  }

Group.java

1  public   class  Group {
2       private  String id ;
3       private  String name ;
...get(),set()省略

4  }

User.hbm.xml

<? xml version="1.0" ?>
<! DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
< hibernate-mapping >
     < class  name ="com.zzn.hibernate.many2One.User"  table ="USER" >
         < id  name ="id"  column ="id" >
             < generator  class ="uuid"   />
         </ id >
         < property  name ="name"   />
         < property  name ="age"   />
         < many-to-one  name ="group"  column ="GROUP_ID"  cascade ="all" />
     </ class >
</ hibernate-mapping >

Group.hbm.xml

<? xml version="1.0" ?>
<! DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
< hibernate-mapping >
     < class  name ="com.zzn.hibernate.many2One.Group"  table ="T_GROUP" >
         < id  name ="id"  column ="id" >
             < generator  class ="uuid"   />
         </ id >
         < property  name ="name"   />
     </ class >
</ hibernate-mapping >

hibernate.cfg.xml

<! DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >

< hibernate-configuration >
     < session-factory >
         < property  name ="hibernate.connection.url" > jdbc:mysql://localhost:3306/hibernate </ property >
         < property  name ="hibernate.connection.driver_class" > com.mysql.jdbc.Driver </ property >
         < property  name ="hibernate.dialect" > org.hibernate.dialect.MySQLDialect </ property >
         < property  name ="hibernate.connection.username" > root </ property >
         < property  name ="hibernate.connection.password" > root </ property >
         < property  name ="hibernate.hbm2ddl.auto" > update </ property >
         < property  name ="show_sql" > true </ property >
        
         < mapping  resource ="com/zzn/hibernate/many2One/User.hbm.xml" />
         < mapping  resource ="com/zzn/hibernate/many2One/Group.hbm.xml" />
     </ session-factory >
</ hibernate-configuration >

test.java

package  com.zzn.hibernate;

import  junit.framework.TestCase;

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

import  com.zzn.hibernate.hibernateUtil.HibernateUtils;
import  com.zzn.hibernate.many2One.Group;
import  com.zzn.hibernate.many2One.User;

public   class  Many2OneTest  extends  TestCase {
    
     public   void  testSaveMany2One(){
        Session session  =   null ;
        Transaction transaction  =   null ;
         try  {
            session  =  HibernateUtils.getSession();
            transaction =  session.beginTransaction();
            Group group  =   new  Group();
            group.setName( " 11111 " );
            User user  =   new  User();
            user.setName( " 刘德华 " );
            user.setAge( 80 );
            user.setGroup(group);
            
            User user2  =   new  User();
            user2.setName( " 周杰伦 " );
            user2.setAge( 25 );
            user2.setGroup(group);
            
            
            session.save(user1);
            session.save(user2);
            transaction.commit();
        }  catch  (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally {
            HibernateUtils.closeSession(session);
        }
    }
     public   void  testUpdateMany2One(){
        Session session  =   null ;
        Transaction transaction  =   null ;
         try  {
            session  =  HibernateUtils.getSession();
            transaction =  session.beginTransaction();
            User user  =  (User)session.get(User. class ,  " 402881e424a9fb110124a9fb124c0001 " );
            Group group  =   new  Group();
            group.setName( " 无敌 " );
            user.setName( " 刘天王 " );
            user.setAge( 22 );
            user.setGroup(group);
            
            session.update(user);
            
            transaction.commit();
        }  catch  (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally {
            HibernateUtils.closeSession(session);
        }
    }
    
    
     public   void  testDeleteMany2One(){
        Session session  =   null ;
        Transaction transaction  =   null ;
         try  {
            session  =  HibernateUtils.getSession();
            transaction =  session.beginTransaction();
            User user  =  (User)session.get(User. class ,  " 402881e424a9e7d80124a9e7d9270001 " );
            session.delete(user);
            transaction.commit();
        }  catch  (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally {
            HibernateUtils.closeSession(session);
        }
    }
    
}