Hibernate多对多关系

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 博客地址：http://www.cnblogs.com/caoyc/p/5598932.html 

代码：

Teacher.java

package com.proc.pojo;

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

public class Student {
    private Integer id;
    private String name;
    private Set<Teacher> teachers=new HashSet<Teacher>();
    public Student() {
    }
    public Student(String name) {
        this.name = name;
    }
    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<Teacher> getTeachers() {
        return teachers;
    }
    public void setTeachers(Set<Teacher> teachers) {
        this.teachers = teachers;
    }
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + "]";
    }
    
}

Student.java

package com.proc.pojo;

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

public class Teacher {
    private Integer id;
    private String name;
    private Set<Student> students=new HashSet<Student>();
    public Teacher() {
    }
    public Teacher(String name) {
        super();
        this.name = name;
    }
    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;
    }
    @Override
    public String toString() {
        return "Teacher [id=" + id + ", name=" + name + "]";
    }
    
}

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.proc.pojo">
    <class name="Student" table="t_student">
        <id name="id" column="id" type="int">
            <generator class="native"></generator>
        </id>
        <property name="name" column="name" type="string" length="20"></property>
        <set name="teachers" table="t_student_teacher">
            <key column="studentId"></key>
            <many-to-many column="teacherId" class="Teacher"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

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">
<hibernate-mapping package="com.proc.pojo">
    <class name="Teacher" table="t_teacher">
        <id name="id" column="id" type="int">
            <generator class="native"></generator>
        </id>
        <property name="name" column="name" type="string" length="20"></property>
        <set name="students" table="t_student_teacher">
            <key column="teacherId"></key>
            <many-to-many column="studentId" class="Student"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

测试代码：

package com.proc.test;

import java.util.Set;

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



import com.proc.pojo.Student;
import com.proc.pojo.Teacher;

public class TestManageToManage {
    private static SessionFactory factory=new Configuration()
    .configure()
    .addClass(Student.class)
    .addClass(Teacher.class)
    .buildSessionFactory();
    
    
    @Test
    public void set(){
    
    Session session=factory.openSession();
    Transaction tran=session.beginTransaction();
    
    Student s1=new Student("张同学");
    Student s2=new Student("王同学");
    
    Teacher t1=new Teacher("曹老师");
    Teacher t2=new Teacher("曾老师");
    
    s1.getTeachers().add(t1);
    s2.getTeachers().add(t1);
    s2.getTeachers().add(t2);
    
    session.save(s1);    
    session.save(s2);
    session.save(t1);
    session.save(t2);
    
    tran.commit();
    session.close();
    }
    
    @Test
    public void get(){
    
    Session session=factory.openSession();
    Transaction tran=session.beginTransaction();
    
    
    Teacher t=session.get(Teacher.class, 2);
    System.out.println(t);
    Set<Student> set=t.getStudents();
    
    System.out.println(set);
    System.out.println("=-------------------------");
    Student s=session.get(Student.class, 2);
    System.out.println(s);
    System.out.println(s.getTeachers());
    
    tran.commit();
    session.close();
    }
}