Hibernate的list:多对多

***************
Student.java
***************

package blog.hibernate.domain;

import java.util.ArrayList;
import java.util.List;

public class Student {

    private int id;
    private String name;
    private List<Teacher> teachers = new ArrayList<Teacher>();

    public List<Teacher> getTeachers() {
        return teachers;
    }

    public void setTeachers(List<Teacher> teachers) {
        this.teachers = teachers;
    }
    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Student{" + "id=" + id + ", name=" + name + '}';
    }
}

************
Student.hbm.xml
************

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="blog.hibernate.domain">
    <class name="Student" table="students">
        <id name="id" column="student_id">
            <generator class="native"></generator>
        </id>
        <property name="name" column="student_name"></property>
                  
         <list name="teachers" table="teacher_student">
             <key column="student_id"></key>
             <list-index column="index" ></list-index>
             <many-to-many class="Teacher" column="teacher_id"></many-to-many>
         </list>
    </class>
</hibernate-mapping>

**************
Teacher.java
**************

package blog.hibernate.domain;

import java.util.ArrayList;
import java.util.List;

public class Teacher {

    private int id;
    private String name;
    private String course;
    private List<Student> students = new ArrayList<Student>();

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getCourse() {
        return course;
    }

    public void setCourse(String course) {
        this.course = course;
    }

    @Override
    public String toString() {
        return "Teacher{" + "id=" + id + ", name=" + name + ", course=" + course + '}';
    }
}

**************
Teacher.hbm.xml
**************

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="blog.hibernate.domain">
    <class name="Teacher" table="teachers">
        <id name="id" column="teacher_id">
            <generator class="native"></generator>
        </id>
        <property name="name" column="teacher_name"></property>
        <property name="course"></property>
                  
         <list name="students" table="teacher_student">
             <key column="teacher_id" ></key>
             <list-index column="index"></list-index>
            <many-to-many class="Student" column="student_id"></many-to-many>
         </list>
    </class>
</hibernate-mapping>

*****************
hibernate.cfg.xml
*****************

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/list</property><!-- ///表示连接本机的数据库//localhost:3306 -->
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">1234</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
           
        <property name="hibernate.hbm2ddl.auto">create</property>
        <property name="hibernate.show_sql">true</property>
                
        <mapping resource="blog/hibernate/domain/Student.hbm.xml"/>
        <mapping resource="blog/hibernate/domain/Teacher.hbm.xml"/>
        
<!--        <mapping resource="blog/hibernate/domain/Nation.hbm.xml"/>
        <mapping resource="blog/hibernate/domain/City.hbm.xml"/>-->
    </session-factory>    
</hibernate-configuration>

*****************
HibernateUtil.java
*****************

package blog.hibernate;

import java.util.logging.Level;
import java.util.logging.Logger;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public final class HibernateUtil {
    
    private static SessionFactory sessionFactory;
    private HibernateUtil(){}
    
    static{
        Configuration cfg = new Configuration();
        sessionFactory =  cfg.configure("hibernate.cfg.xml").buildSessionFactory();
    }
    
    public static SessionFactory getSessionFactory(){
        return sessionFactory;
    }
    
    public static Session getSession(){
        return sessionFactory.openSession();
    }
}

******************
juint test：Many2Many.java
******************

package juint.test;

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

import blog.hibernate.HibernateUtil;
import blog.hibernate.domain.Student;
import blog.hibernate.domain.Teacher;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * list
 * @author Administrator
 */
public class Many2Many {

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
    }

    @Test
    public void test() {
        add();
        query();
    }

    public void add() {
        Teacher t1 = new Teacher();
        t1.setName("t1");

        Teacher t2 = new Teacher();
        t2.setName("t2");

        List<Teacher> ts = new ArrayList<Teacher>();
        ts.add(t1);
        ts.add(t1);

        Student s1 = new Student();
        s1.setName("s1");

        Student s2 = new Student();
        s2.setName("s2");

        List<Student> ss = new ArrayList<Student>();
        ss.add(s1);
        ss.add(s2);
        
        t1.getStudents().add(s1);
        t1.getStudents().add(s2);
        
        t2.getStudents().add(s1);
        t2.getStudents().add(s2);

//        t1.setStudents(ss);
//        t2.setStudents(ss);
        /*    s1.setTeachers(ts);
        s2.setTeachers(ts);*/


        Session session = null;
        Transaction tx = null;
        try {
            session = HibernateUtil.getSession();
            tx = session.beginTransaction();
            session.save(t1);
            session.save(t2);
            session.save(s1);
            session.save(s2);
            tx.commit();
        } catch (Exception e) {
            Logger.getLogger(Many2Many.class.getName()).log(Level.SEVERE, null, e);
            if (tx != null) {
                tx.rollback();
            }
        } finally {
            if (session != null) {
                session.close();
            }
        }
    }

    public void query() {
        Session session = null;
        try {
            session = HibernateUtil.getSession();
            Teacher teacher = (Teacher) session.get(Teacher.class, 1);
            System.out.println(teacher.getStudents().size());
        } catch (Exception e) {
            Logger.getLogger(Many2Many.class.getName()).log(Level.SEVERE, null, e);
        } finally {
            if (session != null) {
                session.close();
            }
        }
    }
}