hibernate中多对多关系映射-优快云博客

本文介绍了一个使用Hibernate框架实现的多对多关系映射案例。通过Job和User两个实体类之间的关联设置，展示了如何在Java应用中映射数据库中的多对多关系，并提供了测试代码来验证这一关系的有效性。

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1.项目示图：

2.Job.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>
<class name="com.eduask.pojo.Job" table="job">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<set name="users" table="user_job" lazy="false">
<key column="job_id"/>
<many-to-many class="com.eduask.pojo.User" column="user_id"></many-to-many>
</set>
</class>
</hibernate-mapping>

3.User.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>
<class name="com.eduask.pojo.User" table="user">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<set name="jobs" table="job_job" lazy="false">
<key column="user_id"/>
<many-to-many class="com.eduask.pojo.Job" column="job_id"></many-to-many>
</set>
</class>
</hibernate-mapping>

4.UserTest.java

package com.eduask.test;
import java.util.HashSet;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Before;
import org.junit.Test;
import com.eduask.pojo.Job;
import com.eduask.pojo.User;
import com.eduask.util.HibernateUtil;
public class UserTest {
private SessionFactory sessionFactory;
@Before
public void setUp(){
sessionFactory=HibernateUtil.getSessionFactory();
}
@Test
public void testUser(){
Session session=sessionFactory.openSession();
Transaction tr=session.beginTransaction();
Job job1=new Job();
job1.setName("软件开发");
session.save(job1);
Job job2=new Job();
job2.setName("软件测试");
session.save(job2);
Set<Job> jobs=new HashSet<Job>();
jobs.add(job1);
jobs.add(job2);
User user=new User();
user.setName("tom");
user.setJobs(jobs);
session.save(user);
tr.commit();
session.close();
}
}