hibernate --------多对多映射

还是用学生和老师来举例子
一个老师可以教多个学生，一个学生也可以有多个老师
（1）先写老师的实体类
package text01;

import java.util.HashSet;
import java.util.Set;

public class Teacher {
private int id;
private String name;
private Set<Student> students = new HashSet<>();

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 Set<Student> getStudents() {
    return students;
}

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

}
还有映射文件
<?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="text01">

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

<id name="id" column="id" type="integer">
<generator class="native"/>
</id>
<property name="name"/>

<set name="students" table="other">

<key column="id"></key>

<many-to-many class="text01.Student" column="num"></many-to-many>
</set>
</class>

</hibernate-mapping>
（2）写学生的实体类以及配置文件

实体类
package text01;

import java.util.HashSet;
import java.util.Set;

public class Student {
private int num;
private String name;
private Set<Teacher> teachers = new HashSet<>();

public int getNum() {
    return num;
}

public void setNum(int num) {
    this.num = num;
}

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;
}

}

映射文件
<?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="text01">

<class name="Student" table="student">
    <id name="num" column="num" type="integer">
        <generator class="native" />
    </id>
    <property name="name" />
    <set name="teachers" table="other">
        <key column="num"></key>
        <many-to-many class="text01.Teacher" column="id"></many-to-many>
    </set>
</class>

</hibernate-mapping>

（3）导入配置文件
<?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>

    <!-- Database connection settings -->
    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="connection.url">jdbc:mysql:///hib</property>
    <property name="connection.username">root</property>
    <property name="connection.password">123456</property>
    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">create</property>
    <!-- SQL dialect -->
    <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>


    <!-- Echo all executed SQL to stdout -->
    <property name="show_sql">true</property>
    <property name="format_sql">true</property>


    <mapping resource="text01/student.hbm.xml" />
    <mapping resource="text01/teacher.hbm.xml" />


</session-factory>

</hibernate-configuration>

（4）
来测试一下
package text;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import text01.Student;
import text01.Teacher;

public class text01 {

public static void main(String[] args) {
    Configuration cfg = new Configuration().configure("hibernate.cfg.xml");
    SessionFactory sessionFactory = cfg.buildSessionFactory();
    Session session = sessionFactory.openSession();
    Transaction ts = session.beginTransaction();

    Teacher teacher = new Teacher();
    Student s1 = new Student();
    Student s2 = new Student();
    s1.setName("666");
    s1.setNum(000);

    s2.setName("6667");
    s2.setNum(0001);
    teacher.setId(1);
    teacher.setName("tom");
    teacher.getStudents().add(s1);
    teacher.getStudents().add(s2);

    session.save(teacher);
    session.save(s1);
    session.save(s2);

    ts.commit();
    session.close();

}

}