HIBERNATE多对多配置

1． 环境，student对lesson，多对多的关系，关系表格：student_lesson(student_id,lesson_id)

2． 配置文件

1） student设为关联维护端

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> < set  name ="lessons"  table ="student_lesson"  inverse =”false”>      
       <key column ="student_id" />      
       < many-to-many  class ="Lesson"  column ="lesson_id"   />    
</ set >

     2） lesson设为逆向关联端

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> < set  name ="students"  table ="student_lesson"  inverse ="true" >          
     < key  column ="lesson_id" />       
     < many-to-many  class ="Student"  column ="student_id" ></ many-to-many >     
</ set >

 

 

3． 推荐设置

一般的将教为主动的一端，配置为关联正向端，本例中学生比课程更为主动，一般不使用 cascade=”true”选项，因为课程不以学生而存在,增加学生时候不会处理课程资料只处理学生和课程的关系，因此 inverse=”false”,cascade=”true”,在增加学生的时候，必须选择库存中的课程而后在存储到学生中

在对多多的关联中无法设置 CASCADE 属性

学生配置：

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> < set  name ="lessons"  table ="student_lesson"  inverse ="false" >               
     < key  column ="student_id" />               
     < many-to-many  class ="Lesson"  column ="lesson_id"   />           
</ set >

期望结果，如果删除学生，参与的课程的资料不删除，与课程的参与关系将自动删除，这个起到与级连相似的结果，同样，选修和退修课程在学生端操作

4． 新增学生

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> Student student  =   new  Student();
student.setStudentId( " 007 " );
student.setName( " ale " );
session.saveOrUpdate(student);

 

5． 新增课程

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />-->  Lesson lesson  =   new  Lesson();    
 lesson.setLessonId( " 20070103 " );    
 lesson.setLessonName( " 激光 " );    
 session.saveOrUpdate(lesson

 

6． 学生选修课程

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> Lesson lesson  =   null ;
Student student  =  (Student)session.load(Student. class , " 005 " );
lesson  =  (Lesson)session.load(Lesson. class , " 20070101 " );
student.getLessons().add(lesson);
lesson  =  (Lesson)session.load(Lesson. class , " 20070103 " );
student.getLessons().add(lesson);

 

7． 学生退出课程选修

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> Lesson lesson  =   null ;
Student student  =  (Student)session.load(Student. class , " 005 " );
lesson  =  (Lesson)session.load(Lesson. class , " 20070101 " );
student.getLessons().add(lesson);
lesson  =  (Lesson)session.load(Lesson. class , " 20070103 " );
student.getLessons().remove(lesson);
session.saveOrUpdate(student);

 

8． 取消课程

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> Lesson lesson  =  (Lesson)session.load(Lesson. class , " 20070103 " );   
session.delete(lesson);

由于配置了学生和课程双向维护关系，删除课程时，也删除了学生与课程的关系

 

9． 删除学生资料

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> Student student  =  (Student)session.load(Student. class , " 005 " );   
session.delete(student);

将级连删除与课程的关系