Hibernate学习�W�记

Tue, 20 Dec 2005 08:20:00 GMT

所有配�|�文仉��要放在classes下面

一:创徏hibernate.cfg.xml文�g�Q�内容如�?

PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">

        java:comp/env/note �q�接池用�Q�如在TOMCAT里配�|�连接池�?BR>        true
        net.sf.hibernate.dialect.MySQLDialect 如果使用mysql��p��P��如果是其他就�Ҏ��hi..property文�g配置

    �q�里是需要映��的hbm文�g

�? One-To-One关系
1):主表的hbm.xml文�g应该�?
#class是子表的�c?BR>2):子表的hbm.xml文�g如下:
#class是主表的
3):每个bean都要有get,set各自的子�c�d��ȝ��.
4):在调用的时候执�?
     user.setPasswd(passwd);
     passwd.setUser(user);
     session.save(user); //只需要保存主�c?BR>
�?many-to-one关系(单向兌��)
1):多数据这边一定要多一个字�D�好兌��主表ID�Q�比如一个房间对多个学生:
room�?id,address
student�?id,name,pid(�q�个字段兌��room表的id),pid必须为可以�ؓ�I?BR> 2):在student.hbm.xml的关�p�Mؓ:
�q�里加个unsaved-value="0",不然会出如下错误:
   javax.servlet.ServletException: a different object with the same identifier value was already associated with the session: 0,
   of class: web.model.vo.RoomBean
3):在测试里�Q�先保存�ȝ��(room,也就是one�q�方),在保存many�q�方�?BR> 4):在studentBean中不需要pid的set,get�Ҏ��,而需要一个对�ȝ��的set,get�Q�如:setRoom(RoomBean xx),getRoom()

�?many-to-one关系(双向兌��)
1):在one(student)�q�方加入set,比如setStudents(Set x),getStudents();
2):在many(room)的room.hbm.xml�?
   �q�里inverse一定要为true�Q�意思是兌��由对�?student)�l�护;



   注意�q�两个hbm.xml的ID处都必须加上unsaved-value="0"
3)客户端程序改�?
                RoomBean room1 = new RoomBean();
  room1.setAddress("chengdu");

  UserBean user = new UserBean();
  user.setName("raoqn");

  UserBean user2 = new UserBean();
  user2.setName("liping");

  UserBean user3 = new UserBean();
  user3.setName("yrq");

  user.setRoom(room1); //�q�里�׃��关系由user�cȝ��护，所以必��setRoom
  user2.setRoom(room1);
  user3.setRoom(room1);

  room1.getUser().add(user);
  room1.getUser().add(user2);
  room1.getUser().add(user3);

  session.save(room1); //只需要保存room1��搞定一�?不用每个对象都save�?/FONT>

�?�?/a> 2005-12-20 16:20 发表评论

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Hibernate学习�W�记