心得6-hibernate级联之多对多单双向剖析

多对多: 学生与课程,以下主要从案例出发，由案例具体解析

单向多对多
Student.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.hbsi.many2many">

<class name="Student" table="student">
<id name="id">
<generator class="native"/>
</id>
<property name="name" column="name"/>

<set name="course" table="student_course" cascade="save-update">
<key column="student_id"/>
<many-to-many column="course_id" class="Course" />
</set>
</class>

</hibernate-mapping>

Course.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.hbsi.many2many">

<class name="Course" table="course">
<id name="id">
<generator class="native"/>
</id>
<property name="name" column="name"/>

</class>
</hibernate-mapping>

测试类
package com.hbsi.many2many;

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

import org.hibernate.Session;
import org.junit.Test;

import com.hbsi.utils.HibernateSessionFactory;

public class TestApp {

Session session = HibernateSessionFactory.getSession();
@Test
public void add(){

session.beginTransaction();

Student student1 = new Student();
student1.setName("keven");

Student student2 = new Student();
student2.setName("jie");

Course course1 = new Course();
course1.setName("english");

Course course2 = new Course();
course2.setName("chinese");

Set<Course> courses = new HashSet<Course>();
courses.add(course1);
courses.add(course2);

student1.setCourse(courses);

session.save(student1);
session.save(student2);
session.save(course1);
session.save(course2);

session.getTransaction().commit();
HibernateSessionFactory.closeSession();

}

@Test
public void find(){
Student student = (Student) session.get(Student.class,1);
Set<Course> courses = student.getCourse();
for(Course course : courses){
System.out.println(student.getName()+"---"+course.getName());
}
}
}

双向多对多
Student.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.hbsi.many2manyboth">

<class name="Student" table="studentboth">
<id name="id">
<generator class="native"/>
</id>
<property name="name" column="name"/>

<set name="course" table="student_courseboth" cascade="save-update">
<key column="student_id"/>
<many-to-many column="course_id" class="Course" />
</set>
</class>

</hibernate-mapping>

Course.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.hbsi.many2manyboth">

<class name="Course" table="courseboth">
<id name="id">
<generator class="native"/>
</id>
<property name="name" column="name"/>

<set name="student" table="student_courseboth" cascade="save-update">
<key column="course_id"/>
<many-to-many class="Student" column="student_id"/>
</set>
</class>
</hibernate-mapping>

测试类

package com.hbsi.many2manyboth;

import java.util.HashSet;
import java.util.Set;
import org.hibernate.Session;
import org.junit.Test;
import com.hbsi.utils.HibernateSessionFactory;

public class TestApp {

Session session = HibernateSessionFactory.getSession();
@Test
public void add(){

session.beginTransaction();

Student student1 = new Student();
student1.setName("keven");

Student student2 = new Student();
student2.setName("jie");

Course course1 = new Course();
course1.setName("english");

Course course2 = new Course();
course2.setName("chinese");

/*达到的添加功能一样，可以从多方的任何一方添加
* Set<Course> courses = new HashSet<Course>();
courses.add(course1);
courses.add(course2);

student1.setCourse(courses);
student2.setCourse(courses);*/

Set<Student> students = new HashSet<Student>();
students.add(student1);
students.add(student2);

course1.setStudent(students);
course2.setStudent(students);

session.save(student1);
session.save(student2);
session.save(course1);
session.save(course2);

session.getTransaction().commit();
HibernateSessionFactory.closeSession();

}
@Test
public void find(){
Student student = (Student) session.get(Student.class,1);
Set<Course> courses = student.getCourse();
for(Course course : courses){
System.out.println(student.getName()+"---"+course.getName());
}
Course course1 = (Course) session.get(Course.class,1);
Set<Student> students = course1.getStudent();
for(Student student1 : students){
System.out.println(course1.getName()+"---"+student1.getName());
}
}

}