package com.xiaostudy.domain;

 import java.util.HashSet;

 import java.util.Set;

 /**

  * Teacher

  *

  * @author xiaostudy

  *

  */

 public class Teacher {

     // id

     private Integer id;

     // 普通属性

     private String name;

     // 另一个类的集合

     private Set<Student> students = new HashSet<Student>();

     // 自动生成get、set方法

     public Integer getId() {

         return id;

     }

     public void setId(Integer id) {

         this.id = id;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this.name = name;

     }

     public Set<Student> getStudents() {

         return students;

     }

     public void setStudents(Set<Student> students) {

         this.students = students;

     }

 }

 package com.xiaostudy.domain;

 import java.util.HashSet;

 import java.util.Set;

 /**

  * Student

  *

  * @author xiaostudy

  *

  */

 public class Student {

     // id

     private Integer id;

     // 普通属性

     private String name;

     // 另一个类的集合

     private Set<Teacher> teachers = new HashSet<Teacher>();

     // 自动生成get、set方法

     public Integer 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 Set<Teacher> getTeachers() {

         return teachers;

     }

     public void setTeachers(Set<Teacher> teachers) {

         this.teachers = teachers;

     }

     public void setId(Integer id) {

         this.id = id;

     }

 }

 <?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">

 <!-- 导入包 -->

 <hibernate-mapping package="com.xiaostudy.domain">

     <!-- name为bean的类名，table为数据库的表名 -->

     <class name="Teacher" table="t_teacher">

         <!-- name为bean的id，column为数据库表的列名 -->

         <id name="id" column="id">

             <!-- 设置自动更新表，表没有的话创建一个，有的话，再判断结构是否为所需，如有没有想应得列，会自动添加列，多余的也不会删除 -->

             <generator class="native"></generator>

         </id>

         <!-- name为普通属性，column为数据库表的列名，type为数据类型 -->

         <property name="name" column="name" type="string"></property>

         <!-- name为bean中另一个类的集合名称，table为多对多中间的表，cascade为级联设置自动更新表 -->

         <set name="students" table="t_teacher_student" cascade="save-update">

             <!-- 自身连接外面的外键 -->

             <key column="tid"></key>

             <!-- column为另一个连接的外键，class为另一个bean的类名 -->

             <many-to-many column="sid" class="Student"></many-to-many>

         </set>

     </class>

 </hibernate-mapping>

 <?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">

 <hibernate-mapping package="com.xiaostudy.domain">

     <class name="Student" table="t_student">

         <id name="id" column="id">

             <generator class="native"></generator>

         </id>

         <property name="name" column="name" type="string"></property>

         <set name="teachers" table="t_teacher_student">

             <key column="sid"></key>

             <many-to-many column="tid" class="Teacher"></many-to-many>

         </set>

     </class>

 </hibernate-mapping>

 <?xml version="1.0" encoding="UTF-8" ?>

 <!DOCTYPE hibernate-configuration PUBLIC

     "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

     "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

 <hibernate-configuration>

     <session-factory>

         <!-- 注册驱动 -->

         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

         <!-- mysql的用户名 -->

         <property name="connection.username">root</property>

         <!-- mysql的用户密码 -->

         <property name="connection.password">123456</property>

         <!-- 连接mysql的某库 -->

         <property name="connection.url">jdbc:mysql://localhost:3306/user</property>

         <!-- 控制台输出sql -->

         <property name="show_sql">true</property>

         <!-- 格式化输出的sql -->

         <property name="format_sql">true</property>

         <!-- 自动提交事务 -->

         <!-- <property name="connection.autocommit">true</property> -->

         <!-- 创建sql表

             update：如果没有表，则创建一个。如果有表，而且表结构一致，那么不改变表。如果表结构不一样，会添加sql表缺少的列，多余的也不会删除。

             create：不管sql表有没有存在，都会重新创建表。

             create-drop：在create的基础上，每次关闭虚拟机时都会把表删除了。

             validate：效验sql表，如果一致，则没有反应，如果不一致了，会抛出异常。

          -->

         <property name="hbm2ddl.auto">update</property>

         <!-- 将Session与线程绑定=> 只有配置了该配置,才能使用getCurrentSession -->

         <property name="current_session_context_class">thread</property>

         <!-- 数据库方言配置 -->

         <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

         <!-- 导入映射文件 -->

         <mapping resource="com/xiaostudy/domain/Teacher.hbm.xml"/>

         <mapping resource="com/xiaostudy/domain/Student.hbm.xml"/>

     </session-factory>

 </hibernate-configuration>

 package com.xiaostudy.test;

 import org.hibernate.classic.Session;

 import com.xiaostudy.domain.Student;

 import com.xiaostudy.domain.Teacher;

 import com.xiaostudy.util.HibernateUtils;

 /**

  * 测试多对多

  *

  * @author xiaostudy

  *

  */

 public class Test1 {

     public static void main(String[] args) {

         //根据hibernate工具类，获取一个全新的Session

         Session session = HibernateUtils.openSession();

         //开始事务

         session.beginTransaction();

         Teacher teacher1 = new Teacher();

         Teacher teacher2 = new Teacher();

         teacher1.setName("t1");

         teacher2.setName("t2");

         Student student1 = new Student();

         Student student2 = new Student();

         student1.setName("s1");

         student2.setName("s2");

         //维护关系

         teacher1.getStudents().add(student1);

         teacher1.getStudents().add(student2);

         teacher2.getStudents().add(student1);

         teacher2.getStudents().add(student2);

         //持久化数据

         session.save(teacher1);

         session.save(teacher2);

         //关闭事务并提交事务

         session.getTransaction().commit();

         //关闭资源

         session.close();

     }

 }