学习Hibernate生成目录树

<?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.bjsxt.hibernate.Node" table="t_node">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="name"/>
        <property name="level"/>
        <property name="leaf"/>
        <many-to-one name="parent" column="pid"/>
        <set name="children" lazy="extra" inverse="true">
        	<key column="pid"/>
        	<one-to-many class="com.bjsxt.hibernate.Node"/>
        </set>
    </class>
</hibernate-mapping>

在一个表中自身映射，使用一个pid列。多个子节点对应一个父节点（parent），一个父节点对应多个子节点，使用set映射，inverse=true，翻转，在多的一端管理。
NodeManager类：

package cn.com.hibernate;

import java.io.File;
import java.util.Iterator;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.Transaction;

public class NodeManager {
	
	private static NodeManager nodeManager= null;
	
	public NodeManager(){
		
	}
	
	public static synchronized NodeManager getInstance(){
		
		if(nodeManager==null){
			nodeManager = new NodeManager();
		}
		return nodeManager;
	}
	
	public void createTree(String dir){
		Session session = HibernateUtil.getSession();
		Transaction tx = session.beginTransaction();
		try{
			File file = new File(dir);
			saveTree(file,session,null,0);
			tx.commit();
		}catch(Exception ex){
			ex.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtil.closeSession(session);
		}
	}
	
	public void saveTree(File file,Session session,Node parent,int level){
		if(file==null||!file.exists()){
			return;
		}
		boolean isLeaf = file.isFile();
		Node node = new Node();
		node.setName(file.getName());
		node.setLeaf(isLeaf);
		node.setParent(parent);
		node.setLevel(level);
		session.save(node);
		File[] subFile = file.listFiles();
		if(subFile!=null && subFile.length!=0){
			for(int i=0;i<subFile.length;i++){
				saveTree(subFile[i],session,node,level+1);
			}
		}
	}
	
	public void printTree(int id){
		Session session = HibernateUtil.getSession();
		Transaction tx = session.beginTransaction();
		try{
			Node root = (Node)session.load(Node.class, 1);
			printNode(root);
			tx.commit();
		}catch(Exception ex){
			ex.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtil.closeSession(session);
		}
	}
	public void printNode(Node root){
		if(root==null){
			return;
		}
		int level = root.getLevel();
		
		if(level>0){
			for(int i=0;i<level;i++){
				System.out.print("   |");
			}
			System.out.print("--");
		}
		System.out.println(root.getName()+(root.isLeaf()?"":"["+root.getChildren().size()+"]"));
		Set<Node> children = root.getChildren();
		for(Iterator<Node> iter = children.iterator();iter.hasNext();){
			Node node = iter.next();
			printNode(node);
		}
	}
	
}

主要是树的生成和树的遍历。
Test类：

package cn.com.hibernate;

import junit.framework.TestCase;

public class createTreeTest extends TestCase {
	public void testCreateTree(){
		NodeManager.getInstance().createTree("D:\\Myeclipse6.5workspace\\Hibernate_tree\\");
	}
	
	public void testPrintTree(){
		NodeManager.getInstance().printTree(1);
	}
}