hibernate的多对多配置

 1 package com.xiaostudy.domain;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * Teacher
 8  * 
 9  * @author xiaostudy
10  *
11  */
12 public class Teacher {
13     // id
14     private Integer id;
15     // 普通属性
16     private String name;
17     // 另一个类的集合
18     private Set<Student> students = new HashSet<Student>();
19 
20     // 自动生成get、set方法
21     public Integer getId() {
22         return id;
23     }
24 
25     public void setId(Integer id) {
26         this.id = id;
27     }
28 
29     public String getName() {
30         return name;
31     }
32 
33     public void setName(String name) {
34         this.name = name;
35     }
36 
37     public Set<Student> getStudents() {
38         return students;
39     }
40 
41     public void setStudents(Set<Student> students) {
42         this.students = students;
43     }
44 
45 }

 1 package com.xiaostudy.domain;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * Student
 8  * 
 9  * @author xiaostudy
10  *
11  */
12 public class Student {
13     // id
14     private Integer id;
15     // 普通属性
16     private String name;
17     // 另一个类的集合
18     private Set<Teacher> teachers = new HashSet<Teacher>();
19 
20     // 自动生成get、set方法
21     public Integer getId() {
22         return id;
23     }
24 
25     public void setId(int id) {
26         this.id = id;
27     }
28 
29     public String getName() {
30         return name;
31     }
32 
33     public void setName(String name) {
34         this.name = name;
35     }
36 
37     public Set<Teacher> getTeachers() {
38         return teachers;
39     }
40 
41     public void setTeachers(Set<Teacher> teachers) {
42         this.teachers = teachers;
43     }
44 
45     public void setId(Integer id) {
46         this.id = id;
47     }
48 
49 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC 
 3     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 <!-- 导入包 -->
 6 <hibernate-mapping package="com.xiaostudy.domain">
 7     <!-- name为bean的类名，table为数据库的表名 -->
 8     <class name="Teacher" table="t_teacher">
 9         <!-- name为bean的id，column为数据库表的列名 -->
10         <id name="id" column="id">
11             <!-- 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 -->
12             <generator class="native"></generator>
13         </id>
14         <!-- name为普通属性，column为数据库表的列名，type为数据类型 -->
15         <property name="name" column="name" type="string"></property>
16         <!-- 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 -->
17         <set name="students" table="t_teacher_student" cascade="save-update">
18             <!-- 自身连接外面的外键 -->
19             <key column="tid"></key>
20             <!-- column为另一个连接的外键，class为另一个bean的类名 -->
21             <many-to-many column="sid" class="Student"></many-to-many>
22         </set>
23     </class>
24 </hibernate-mapping>

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC 
 3     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 <hibernate-mapping package="com.xiaostudy.domain">
 6     <class name="Student" table="t_student">
 7         <id name="id" column="id">
 8             <generator class="native"></generator>
 9         </id>
10         <property name="name" column="name" type="string"></property>
11         <set name="teachers" table="t_teacher_student">
12             <key column="sid"></key>
13             <many-to-many column="tid" class="Teacher"></many-to-many>
14         </set>
15     </class>
16 </hibernate-mapping>

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE hibernate-configuration PUBLIC
 3     "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4     "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
 5 
 6 <hibernate-configuration>
 7     <session-factory>
 8         <!-- 注册驱动 -->
 9         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
10         <!-- mysql的用户名 -->
11         <property name="connection.username">root</property>
12         <!-- mysql的用户密码 -->
13         <property name="connection.password">123456</property>
14         <!-- 连接mysql的某库 -->
15         <property name="connection.url">jdbc:mysql://localhost:3306/user</property>
16         <!-- 控制台输出sql -->
17         <property name="show_sql">true</property>
18         <!-- 格式化输出的sql -->
19         <property name="format_sql">true</property>
20         <!-- 自动提交事务 -->
21         <!-- <property name="connection.autocommit">true</property> -->
22         <!-- 创建sql表
23             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。
24             create：不管sql表有没有存在，都会重新创建表。
25             create-drop：在create的基础上，每次关闭虚拟机时都会把表删除了。
26             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。
27          -->
28         <property name="hbm2ddl.auto">update</property>
29         <!-- 将Session与线程绑定=> 只有配置了该配置,才能使用getCurrentSession -->
30         <property name="current_session_context_class">thread</property>
31         <!-- 数据库方言配置 -->
32         <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
33         <!-- 导入映射文件 -->
34         <mapping resource="com/xiaostudy/domain/Teacher.hbm.xml"/>
35         <mapping resource="com/xiaostudy/domain/Student.hbm.xml"/>
36     </session-factory>
37 </hibernate-configuration>

 1 package com.xiaostudy.test;
 2 
 3 import org.hibernate.classic.Session;
 4 
 5 import com.xiaostudy.domain.Student;
 6 import com.xiaostudy.domain.Teacher;
 7 import com.xiaostudy.util.HibernateUtils;
 8 
 9 /**
10  * 测试多对多
11  * 
12  * @author xiaostudy
13  *
14  */
15 public class Test1 {
16 
17     public static void main(String[] args) {
18         //根据hibernate工具类，获取一个全新的Session
19         Session session = HibernateUtils.openSession();
20         //开始事务
21         session.beginTransaction();
22         Teacher teacher1 = new Teacher();
23         Teacher teacher2 = new Teacher();
24         teacher1.setName("t1");
25         teacher2.setName("t2");
26 
27         Student student1 = new Student();
28         Student student2 = new Student();
29         student1.setName("s1");
30         student2.setName("s2");
31 
32         //维护关系
33         teacher1.getStudents().add(student1);
34         teacher1.getStudents().add(student2);
35         teacher2.getStudents().add(student1);
36         teacher2.getStudents().add(student2);
37 
38         //持久化数据
39         session.save(teacher1);
40         session.save(teacher2);
41 
42         //关闭事务并提交事务
43         session.getTransaction().commit();
44         //关闭资源
45         session.close();
46     }
47 
48 }