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;
}
}

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;
}
}

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);
}
}
}