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();

}

}