1. 树实现通过pid进行指向上一层来实现，实体类代码如下
package com.test.model;import java.util.HashSet;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;@Entitypublic class Org { ???private int id; ???private String name; ???private Set<Org> children = new HashSet<Org>(); ???private Org parent; ???????@Id ???@GeneratedValue ???public int getId() { ???????return id; ???} ???public void setId(int id) { ???????this.id = id; ???} ???public String getName() { ???????return name; ???} ???public void setName(String name) { ???????this.name = name; ???} ???????@OneToMany(mappedBy="parent", cascade=CascadeType.ALL, fetch=FetchType.EAGER) ???public Set<Org> getChildren() { ???????return children; ???} ???public void setChildren(Set<Org> children) { ???????this.children = children; ???} ???????@ManyToOne ???@JoinColumn(name="parent_Id") ???public Org getParent() { ???????return parent; ???} ???public void setParent(Org parent) { ???????this.parent = parent; ???}}2.测试类代码如下， 查询时可通过递归进行查询
package com.test.test;import org.hibernate.classic.Session;import com.test.Util.HibernateUtil;import com.test.model.Org;public class StudentManager { ???public static void main(String[] args) { ???????new StudentManager().testSave(); ???} ???????public void testSave() { ???????Session session = HibernateUtil.getSessionFactory().getCurrentSession(); ???????session.beginTransaction(); ???????????????Org o = new Org(); ???????o.setName("总公司"); ???????????????Org o1 = new Org(); ???????o1.setName("分公司1"); ???????????????Org o2 = new Org(); ???????o2.setName("分公司2"); ???????????????Org o21 = new Org(); ???????o21.setName("分公司2_1"); ???????????????Org o22 = new Org(); ???????o22.setName("分公司2_2"); ???????????????o.getChildren().add(o1); ???????o.getChildren().add(o2); ???????????????o1.setParent(o); ???????????????o2.setParent(o); ???????o2.getChildren().add(o21); ???????o2.getChildren().add(o22); ???????????????o21.setParent(o2); ???????o22.setParent(o2); ???????????????session.save(o); ???????testLoad(); ???????session.getTransaction().commit(); ???} ???????public void testLoad() { ???????Session session = HibernateUtil.getSessionFactory().getCurrentSession(); ???????session.beginTransaction(); ???????Org org = (Org)session.load(Org.class, 1); ???????print(org, 0); ???????????} ???private void print(Org org, int level) { ???????String str = "----"; ???????for(int i=0; i<level; i++) { ???????????System.out.print(str); ???????} ???????????????System.out.println(org.getName()); ???????level++; ???????for(Org o:org.getChildren()) { ???????????print(o, level); ???????} ???}} ???hibernate树
原文地址：https://www.cnblogs.com/redhat0019/p/8480051.html