对象关系_many2many

jdbc:

package demo.test.many2many;

import java.util.HashSet;
import java.util.Set;

public class Student {
    private int Stu_id;
    private String Stu_name;
    private Set<Teacher> teacher = new HashSet<>();
    public int getStu_id() {
        return Stu_id;
    }
    public void setStu_id(int stu_id) {
        Stu_id = stu_id;
    }
    public String getStu_name() {
        return Stu_name;
    }
    public void setStu_name(String stu_name) {
        Stu_name = stu_name;
    }
    public Set<Teacher> getTeacher() {
        return teacher;
    }
    public void setTeacher(Set<Teacher> teacher) {
        this.teacher = teacher;
    }
    public Student(int stu_id, String stu_name, Set<Teacher> teacher) {
        Stu_id = stu_id;
        Stu_name = stu_name;
        this.teacher = teacher;
    }
    public Student(String stu_name, Set<Teacher> teacher) {
        Stu_name = stu_name;
        this.teacher = teacher;
    }
    public Student(String stu_name) {
        Stu_name = stu_name;
    }
    @Override
    public String toString() {
        return "Student [Stu_id=" + Stu_id + ", Stu_name=" + Stu_name + "]";
    }
    
}

package demo.test.many2many;

import java.util.HashSet;
import java.util.Set;

public class Teacher {
    private int tea_id;
    private String name;
    private Set<Student> student = new HashSet<>();

    public Teacher() {
    }

    public int getTea_id() {
        return tea_id;
    }

    public void setTea_id(int tea_id) {
        this.tea_id = tea_id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set<Student> getStudent() {
        return student;
    }

    public void setStudent(Set<Student> student) {
        this.student = student;
    }

    public Teacher(int tea_id, String name, Set<Student> student) {
        this.tea_id = tea_id;
        this.name = name;
        this.student = student;
    }
    public Teacher(String name, Set<Student> student) {
        this.name = name;
        this.student = student;
    }
    public Teacher(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Teacher [tea_id=" + tea_id + ", name=" + name + "]";
    }
    

}

.xml文件

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="demo.test.many2many">
<!-- 根据包名找类,根据类名加载对应的类 -->
    <class name="Student" table="s_student">
        <id name="Stu_id" column="stu_id">
            <generator class="native"/>
        </id>
        <property name="Stu_name" column="Stu_name"/>
        <!--
            t_tea_stu:中间表的表名
            当前对象对应的ID列名和中间表 
            设置中间表的那一列与当前表关联
        -->
        
        <set name="teacher" table="t_tea_stu">
            <key column="id_stu" /><!-- 设置对面的外键  -->
            <!-- class="对方的类名" column="" -->
            <many-to-many class="Teacher" column="id_tea"/>
        </set>
    
    
    
    </class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="demo.test.many2many">
<!-- 根据包名找类,根据类名加载对应的类 -->
    <class name="Teacher" table="t_teacher">
        <id name="tea_id" column="t_id">
            <generator class="native"/>
        </id>
        <property name="name" column="t_name"/>
        
            <!--
                 inverse:管理权
                ERROR:Duplicate entry '1-2' for key 'PRIMARY'
            -->
        <set name="student" table="t_tea_stu" >
            <key column="id_tea"/> <!-- 设置对面的外键  -->
            <many-to-many class="Student" column="id_stu"/>
        </set>
    </class>
</hibernate-mapping>

test测试类:

package demo.test.many2many;

import org.hibernate.Session;
import org.junit.Test;

import demo.test.utiltool.UtilTool;

public class Many2Many {
    //关联关系one2one;one2many;many2one;many2many
    @Test
    public void testsave(){
        Teacher tea1 = new Teacher("张老师");
        Teacher tea2 = new Teacher("刘老师");
        Student stu1 = new Student("王同学");
        Student stu2 = new Student("李同学");
        //将学生添加给老师
        tea1.getStudent().add(stu1);
        tea1.getStudent().add(stu2);
        tea2.getStudent().add(stu1);
        tea2.getStudent().add(stu2);
        
        Session session = UtilTool.getInstance().getSession();
        session.beginTransaction();
        
        session.save(stu1);
        session.save(stu2);
        session.save(tea1);
        session.save(tea2);
        session.getTransaction().commit();
        session.close();
        
        
    }
}

最后,记得将各.hbm.xml文件引入cfg.xml