hibernate多对多映射关系实现

Course.hbm.xml:

<?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="model">

<class name="Course" table="t_course">
        <id name="id" column="courseId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="courseName"></property>
    </class>

</hibernate-mapping>

Course2.hbm.xml:

<?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="model">

<class name="Course2" table="t_course2">
        <id name="id" column="courseId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="courseName"></property>
        <set name="students" table="student_course2" inverse="true">
            <key column="course_id"></key>
            <many-to-many class="model.Student2" column="student_id"></many-to-many>
        </set>
    </class>

</hibernate-mapping>

Student.hbm.xml:

<?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="model">

<class name="Student" table="t_student">
        <id name="id" column="studentId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="studentName"></property>
        <set name="courses" table="student_course" cascade="save-update">
            <key column="student_id"></key>
            <many-to-many class="model.Course" column="course_id"></many-to-many>
        </set>
    </class>

</hibernate-mapping>

Student2.hbm.xml:

<?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="model">

<class name="Student2" table="t_student2">
        <id name="id" column="studentId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="studentName"></property>
        <set name="courses" table="student_course2" cascade="save-update">
            <key column="student_id"></key>
            <many-to-many class="model.Course2" column="course_id"></many-to-many>
        </set>
    </class>

</hibernate-mapping>

StudentTest.java:

package service;

import java.util.Iterator;
import java.util.Set;

import model.Course;
import model.Course2;
import model.Student;
import model.Student2;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import util.HibernateUtil;

public class StudentTest {

SessionFactory sessionfactory=HibernateUtil.getSessionFactory();//获取Session工厂
    private Session session;
    
    @Before
    public void setUp() throws Exception {
        session=sessionfactory.openSession();//生成一个新的session
        session.beginTransaction();//开启事务
    }

@After
    public void tearDown() throws Exception {
        session.getTransaction().commit();//提交事务
        session.close();//关闭session
    }

@Test
    public void testSave1(){
        Course course1=new Course();
        course1.setName("语文");
        
        Course course2=new Course();
        course2.setName("数学");
        
        Student student1=new Student();
        student1.setName("一号");
        student1.getCourses().add(course1);
        student1.getCourses().add(course2);
        
        Student student2=new Student();
        student2.setName("二号");
        student2.getCourses().add(course1);
        student2.getCourses().add(course2);
        
        session.save(student1);
        session.save(student2);
    }
    
    @Test
    public void testLoad1(){
        Student student=(Student) session.get(Student.class,1);
        Set<Course> courses=(Set<Course>)student.getCourses();
        Iterator it=courses.iterator();
        while(it.hasNext()){
            Course c=(Course) it.next();
            System.out.println(c.getName());
        }
    }
    
    @Test
    public void testSave2(){
        Course2 course1=new Course2();
        course1.setName("语文");
        
        Course2 course2=new Course2();
        course2.setName("数学");
        
        Student2 student1=new Student2();
        student1.setName("三号");
        student1.getCourses().add(course1);
        student1.getCourses().add(course2);
        
        Student2 student2=new Student2();
        student2.setName("四号");
        student2.getCourses().add(course1);
        student2.getCourses().add(course2);
        
        session.save(student1);
        session.save(student2);
    }
    
    @Test
    public void testLoad2(){
        Course2 course=(Course2) session.get(Course2.class,1);
        Set<Student2> students=(Set<Student2>)course.getStudents();
        Iterator it=students.iterator();
        while(it.hasNext()){
            Student2 s=(Student2) it.next();
            System.out.println(s.getName());
        }
    }
}