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();
    }
    
}