hibernate的基础学习--多对多关联

多对多采用学生老师模型进行测试

学生配置文件：

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-mapping PUBLIC
     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 <!-- 映射配置 -->
 <hibernate-mapping>
     <class name="hib.po.Student" table="t_student">
         <id name="stuId" column="stu_id">
             <generator class="uuid"></generator>
         </id>
         <property name="stuName" column="stuname"></property>

         <!--  和老师的关联关系：teachers
             name：关联关系属性名称
             table：中间表名称
             inverse：关联关系的维护权
             cascade:级联 delete update
         -->
         <set name="teachers" table="t_stu_tea">
             <!--column:中间表中指向当前模型对应表(t_student)的外键名-->
             <key column="stu_id"></key>
             <!--
                 class：关联关系字段集合的元素的类型
                 column:中间表指向当前模型关联的模型对应表（t_student）的外键
              -->
             <many-to-many class="hib.po.Teacher" column="tea_id"></many-to-many>
         </set>
     </class>
 </hibernate-mapping>

老师配置文件：

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-mapping PUBLIC
     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 <!-- 映射配置 -->
 <hibernate-mapping>
     <class name="hib.po.Teacher" table="t_teacher">
         <id name="teaId" column="tea_id">
             <generator class="uuid"></generator>
         </id>
         <property name="teaName" column="teaname"></property>

         <!-- 和学生的关联关系：students
             name：关联关系属性名称
             table：中间表名称（必须和对应关联表中配置一致）
             放弃维护关系 inverse="true"
         -->
         <set name="students" table="t_stu_tea">
             <!--column:中间表中指向当前模型对应表（t_teacher)的外键名-->
             <key column="tea_id"></key>

             <!--
                 class：关联关系字段集合的元素的类型
                 column:中间表指向当前模型关联的模型对应表（t_student）的外键
              -->
             <many-to-many class="hib.po.Student" column="stu_id"></many-to-many>
         </set>
     </class>
 </hibernate-mapping>

测试方法：

 public class TestHibernate {

     /**
      * 添加数据记录
      */
     @Test
     public void addTeacherStudent() {
         SessionFactory sf = H3Util.getSessionFactory();
         Session session = sf.openSession();
         Transaction ts = session.beginTransaction();

         Student stu1 = new Student(null, "张三", null);
         Student stu2 = new Student(null, "李四", null);

         Teacher tea1 = new Teacher(null, "张老师", null);
         Teacher tea2 = new Teacher(null, "李老师", null);

         session.save(stu1);
         session.save(stu2);
         session.save(tea1);
         session.save(tea2);

         ts.commit();
         session.close();
     }
     @Test /* 关联关系*/
     public void updateStudent() {
         SessionFactory sf = H3Util.getSessionFactory();
         Session session = sf.openSession();
         Transaction ts = session.beginTransaction();

         Teacher t1 = (Teacher) session.get(Teacher.class, "4028810a57d19c510157d19c55650002");
         Student s1 = (Student) session.get(Student.class, "4028810a57d19c510157d19c554a0000");
         Student s2 = (Student) session.get(Student.class, "4028810a57d19c510157d19c55650001");
         Set<Teacher> st1 = s1.getTeachers();
         st1.add(t1);
         Set<Teacher> st2 = s2.getTeachers();
         st2.add(t1);
         s1.setTeachers(st1);
         s2.setTeachers(st2);
         session.update(s1);
         session.update(s2);

         ts.commit();
         session.close();
     }
     @Test
     public void delStudent1() {
         SessionFactory sf = H3Util.getSessionFactory();
         Session session = sf.openSession();
         Transaction ts = session.beginTransaction();

         //张三
         Student stu = (Student) session.get(Student.class, "4028810a57d19c510157d19c554a0000");

         //先删除关联关系（中间表字段）再删除本对象
         session.delete(stu);

         ts.commit();
         session.close();
     }

 }