Hibernate/JPA 单表一对多关系映射

这里以组织机构为例：

表结构

字段	类型	备注
OrgId	NUMBER(10)	主键
OrgName	Varchar2(128)	组织机构名称
ParentId	NUMBER(10)	父机构ID，外键参考OrgId

实体类：Org

 

import org.hibernate.Session;

import org.junit.Before;

import org.junit.Test;

import commons.utils.HibernateUtil;

 

public class TestOrg {

    @Before

    private void test1() {

       Session session = HibernateUtil.getCurrentSession();

       session.getTransaction().begin();

       Org o, o1, o2, o11, o12;

       o = new Org("org");

       o.setParentId((Org) session.get(Org.class, new Long(-100)));

       o1 = new Org("-org1");

       o2 = new Org("-org2");

       o11 = new Org("--org11");

       o12 = new Org("--org12");

       o11.setParentId(o1);

       o12.setParentId(o1);

       o1.setParentId(o);

       o2.setParentId(o);

       session.save(o);

       session.save(o1);

       session.save(o2);

       session.save(o11);

       session.save(o12);

       session.getTransaction().commit();

       session.close();

    }

 

    @Test

    private void test2() {

       Session session = HibernateUtil.getCurrentSession();

       session.getTransaction().begin();

       Org o = (Org) session.createQuery("from Org o where o.parentId is null").uniqueResult();

       System.out.println(o.getOrgName() + "-" + o.getOrgId());

       Org o1 = new Org("-org3");

       o1.setParentId(o);

       session.save(o1);

       session.getTransaction().commit();

       session.close();

    }

}