hibernate的多对多配置

Teacher.java

 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;
     }

 }

Student.java

 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;
     }

 }

Teacher.hbm.xml

 <?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>

Student.hbm.xml

 <?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>

hibernate.cfg.xml

 <?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>

Test1.java

 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();
     }

 }

码云：https://gitee.com/xiaostudy2/hibernate_manyToMany_demo/attach_files

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