一对多自身关联双向映射

一个一对多双向自身关联映射案例

<?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.bjpowernode.hibernate.Category" table="t_category">

		<id name="id">

			<generator class="native"/>

		</id>

		<property name="name"/>

		<many-to-one name="parentCategory" column="category_id" cascade="save-update"/>

		<set name="childCategory" cascade="save-update">

		    <key column="category_id"/>

		    <one-to-many class="com.bjpowernode.hibernate.Category"/>

		</set>

	</class>

</hibernate-mapping>

 

package com.bjpowernode.hibernate;

import java.io.Serializable;

import java.util.HashSet;

import java.util.Set;

public class Category implements Serializable{

    private Integer id;

    private String name;

    private Category parentCategory;

    private Set childCategory = new HashSet();

	public Integer getId() {

		return id;

	}

	private void setId(Integer id) {

		this.id = id;

	}

	public String getName() {

		return name;

	}

	public void setName(String name) {

		this.name = name;

	}

	public Category getParentCategory() {

		return parentCategory;

	}

	public void setParentCategory(Category parentCategory) {

		this.parentCategory = parentCategory;

	}

	public Set getChildCategory() {

		return childCategory;

	}

	public void setChildCategory(Set childCategory) {

		this.childCategory = childCategory;

	}   

}

工具类

package com.bjpowernode.hibernate;



import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;



public class HibernateUtils {



	private static SessionFactory factory;

	

	static {

		try {

			//读取hibernate.cfg.xml文件

			Configuration cfg = new Configuration().configure();

			

			//建立SessionFactory

			factory = cfg.buildSessionFactory();

		}catch(Exception e) {

			e.printStackTrace();

		}

	}

	

	public static Session getSession() {

		return factory.openSession();

	} 

	

	public static void closeSession(Session session) {

		if (session != null) {

			if (session.isOpen()) {

				session.close();

			}

		}

	}

	

	public static SessionFactory getSessionFactory() {

		return factory;

	}

}

测试类：

package com.bjpowernode.hibernate;



import java.util.HashSet;



import org.hibernate.Session;

import junit.framework.TestCase;



public class Test extends TestCase {

   public void addCategory(){

	   //创建session

	   Session session = null;

	   try{

		  session = HibernateUtils.getSession();

		  session.beginTransaction();

		  

		  Category food = new Category();

		  food.setName("food");

		 		  

		  Category vegetable = new Category();

		  vegetable.setName("vegetable");

		  

		  Category fruit = new Category();

		  fruit.setName("fruit");

		

		  Category tomato = new Category();

		  tomato.setName("tomato");

	

		  Category apple = new Category();

		  apple.setName("apple");

	

		  Category orange = new Category();

		  orange.setName("orange");

		  

		  food.getChildCategory().add(vegetable);

		  vegetable.setParentCategory(food);

		  

		  food.getChildCategory().add(fruit);

		  fruit.setParentCategory(food);

		  

		  fruit.getChildCategory().add(apple);

		  apple.setParentCategory(fruit);

		  

		  fruit.getChildCategory().add(orange);

		  orange.setParentCategory(fruit);

		  

		  fruit.getChildCategory().add(tomato);

		  tomato.setParentCategory(fruit);

		  

		  session.save(food);	  

		  session.beginTransaction().commit();

	   } catch(Exception e){

		   session.beginTransaction().rollback();

		   e.printStackTrace();

	   } finally{

		   HibernateUtils.closeSession(session);

	   }

   }

   public void modifyCategory(){

	   //创建session

	   Session session = null;

	   try{

		  session = HibernateUtils.getSession();

		  session.beginTransaction();

		  

		  Category tomato = (Category)session.get(Category.class, 5);

		  Category vegetable = (Category)session.get(Category.class, 6);

		  Category fruit = (Category)session.get(Category.class, 2);

 

		  fruit.getChildCategory().remove(tomato);

		  vegetable.getChildCategory().add(tomato);

		  tomato.setParentCategory(vegetable);

		  

		  session.beginTransaction().commit();

	   } catch(Exception e){

		   session.beginTransaction().rollback();

		   e.printStackTrace();

	   } finally{

		   HibernateUtils.closeSession(session);

	   }

   }

}