本文介绍了一种使用Hibernate框架实现树型结构数据存储的方法，包括配置文件、实体类定义、会话工厂创建及树型结构数据的递归创建与查询。
1.映射关系：树型结构中当前节点与其父节点是many-to-one的关系，与其子节点是one-to-many的关系；
2.创建：将节点的所有子节点递归存入数据库；
3.查询：递归查找节点的所有子节点；
hibernate.cfg.xml:
01.
<? xml version = '1.0' encoding = 'UTF-8' ?>
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<!DOCTYPE hibernate-configuration PUBLIC
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"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
05.
06.
<!-- Generated by MyEclipse Hibernate Tools. -->
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< hibernate-configuration >
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09.
< session-factory >
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< property name = "connection.username" >scott</ property >
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< property name = "connection.url" >
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jdbc:oracle:thin:@127.0.0.1:1521:MGC
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</ property >
14.
< property name = "dialect" >
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org.hibernate.dialect.Oracle9Dialect
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</ property >
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< property name = "myeclipse.connection.profile" >MGC</ property >
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< property name = "connection.password" >tiger</ property >
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< property name = "connection.driver_class" >
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oracle.jdbc.driver.OracleDriver
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</ property >
22.
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< property name = "show_sql" >false</ property >
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< mapping resource = "cn/edu/ahau/mgc/hibernate/pojo/Node.hbm.xml" />
25.
26.
</ session-factory >
27.
28.
</ hibernate-configuration >
Node.java:
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package cn.edu.ahau.mgc.hibernate.pojo;
02.
03.
import java.util.Set;
04.
05.
public class Node {
06.
07.
private long id;
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private String name;
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private int level;
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private boolean leaf;
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private Node parent;
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private Set<Node> children;
13.
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public long getId() {
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return id;
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}
17.
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public void setId( long id) {
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this .id = id;
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}
21.
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public String getName() {
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return name;
24.
}
25.
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public void setName(String name) {
27.
this .name = name;
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}
29.
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public int getLevel() {
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return level;
32.
}
33.
34.
public void setLevel( int level) {
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this .level = level;
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}
37.
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public boolean isLeaf() {
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return leaf;
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}
41.
42.
public void setLeaf( boolean leaf) {
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this .leaf = leaf;
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}
45.
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public Node getParent() {
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return parent;
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}
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public void setParent(Node parent) {
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this .parent = parent;
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}
53.
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public Set<Node> getChildren() {
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return children;
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}
57.
58.
public void setChildren(Set<Node> children) {
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this .children = children;
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}
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}
Node.hbm.xml:
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<? xml version = "1.0" encoding = "utf-8" ?>
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<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
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<!--
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Mapping file autogenerated by MyEclipse Persistence Tools
06.
-->
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< hibernate-mapping >
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< class name = "cn.edu.ahau.mgc.hibernate.pojo.Node" table = "TREE_NODE" schema = "SCOTT" >
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< id name = "id" type = "java.lang.Long" >
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< column name = "ID" precision = "22" scale = "0" />
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< generator class = "native" />
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</ id >
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< property name = "name" type = "java.lang.String" column = "NAME" />
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< property name = "level" type = "java.lang.Integer" column = "LEVELNO" />
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< property name = "leaf" type = "java.lang.Boolean" column = "LEAF" />
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< many-to-one name = "parent" column = "PID" />
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< set name = "children" >
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< key column = "PID" />
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< one-to-many class = "cn.edu.ahau.mgc.hibernate.pojo.Node" />
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</ set >
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</ class >
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</ hibernate-mapping >
HibernateSessionFactory.java:
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package cn.edu.ahau.mgc.hibernate.many2one.factory;
002.
003.
import org.hibernate.HibernateException;
004.
import org.hibernate.Session;
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import org.hibernate.cfg.Configuration;
006.
007.
/**
008.
* Configures and provides access to Hibernate sessions, tied to the
009.
* current thread of execution. Follows the Thread Local Session
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* pattern, see {@link http://hibernate.org/42.html ;}.
011.
*/
012.
public class HibernateSessionFactory {
013.
014.
/**
015.
* Location of hibernate.cfg.xml file.
016.
* Location should be on the classpath as Hibernate uses
017.
* #resourceAsStream style lookup for its configuration file.
018.
* The default classpath location of the hibernate config file is
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* in the default package. Use #setConfigFile() to update
020.
* the location of the configuration file for the current session.
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*/
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private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml" ;
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private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
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private static Configuration configuration = new Configuration();
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private static org.hibernate.SessionFactory sessionFactory;
026.
private static String configFile = CONFIG_FILE_LOCATION;
027.
028.
static {
029.
try {
030.
configuration.configure(configFile);
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sessionFactory = configuration.buildSessionFactory();
032.
} catch (Exception e) {
033.
System.err
034.
.println( "%%%% Error Creating SessionFactory %%%%" );
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e.printStackTrace();
036.
}
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}
038.
private HibernateSessionFactory() {
039.
}
040.
041.
/**
042.
* Returns the ThreadLocal Session instance. Lazy initialize
043.
* the <code>SessionFactory</code> if needed.
044.
*
045.
* @return Session
046.
* @throws HibernateException
047.
*/
048.
public static Session getSession() throws HibernateException {
049.
Session session = (Session) threadLocal.get();
050.
051.
if (session == null || !session.isOpen()) {
052.
if (sessionFactory == null ) {
053.
rebuildSessionFactory();
054.
}
055.
session = (sessionFactory != null ) ? sessionFactory.openSession()
056.
: null ;
057.
threadLocal.set(session);
058.
}
059.
060.
return session;
061.
}
062.
063.
/**
064.
* Rebuild hibernate session factory
065.
*
066.
*/
067.
public static void rebuildSessionFactory() {
068.
try {
069.
configuration.configure(configFile);
070.
sessionFactory = configuration.buildSessionFactory();
071.
} catch (Exception e) {
072.
System.err
073.
.println( "%%%% Error Creating SessionFactory %%%%" );
074.
e.printStackTrace();
075.
}
076.
}
077.
078.
/**
079.
* Close the single hibernate session instance.
080.
*
081.
* @throws HibernateException
082.
*/
083.
public static void closeSession() throws HibernateException {
084.
Session session = (Session) threadLocal.get();
085.
threadLocal.set( null );
086.
087.
if (session != null ) {
088.
session.close();
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}
090.
}
091.
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/**
093.
* return session factory
094.
*
095.
*/
096.
public static org.hibernate.SessionFactory getSessionFactory() {
097.
return sessionFactory;
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}
099.
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/**
101.
* return session factory
102.
*
103.
* session factory will be rebuilded in the next call
104.
*/
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public static void setConfigFile(String configFile) {
106.
HibernateSessionFactory.configFile = configFile;
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sessionFactory = null ;
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}
109.
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/**
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* return hibernate configuration
112.
*
113.
*/
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public static Configuration getConfiguration() {
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return configuration;
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}
117.
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}
ExportToDBCreate.java:
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package cn.edu.ahau.mgc.hibernate.export;
02.
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import org.hibernate.cfg.Configuration;
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import org.hibernate.tool.hbm2ddl.SchemaExport;
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public class ExportToDBCreate {
07.
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public static void main(String[] args) {
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Configuration cfg = new Configuration().configure();
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SchemaExport export = new SchemaExport(cfg);
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export.create( true , true );
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}
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}
NodeManager.java:
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package cn.edu.ahau.mgc.hibernate.export;
02.
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import java.io.File;
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import java.util.Iterator;
05.
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import org.hibernate.Session;
07.
08.
import cn.edu.ahau.mgc.hibernate.factory.HibernateSessionFactory;
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import cn.edu.ahau.mgc.hibernate.pojo.Node;
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public class NodeManager {
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private static NodeManager nodeManager;
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private NodeManager() {
16.
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}
18.
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public static synchronized NodeManager getInstance() {
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if (nodeManager == null ) {
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nodeManager = new NodeManager();
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}
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return nodeManager;
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}
25.
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public void createTree(String filePath) {
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Session session = null ;
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try {
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session = HibernateSessionFactory.getSession();
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session.beginTransaction();
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File root = new File(filePath);
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saveTree(root, 0 , null , session);
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session.getTransaction().commit();
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} catch (Exception e) {
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e.printStackTrace();
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session.getTransaction().rollback();
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} finally {
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HibernateSessionFactory.closeSession();
42.
}
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}
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public void saveTree(File root, int level, Node parent, Session session) {
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boolean leaf = root.isFile() || root.listFiles().length == 0 ;
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Node node = new Node();
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node.setName(root.getName());
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node.setLevel(level);
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node.setLeaf(leaf);
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node.setParent(parent);
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session.save(node);
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if (!leaf) {
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for ( int i = 0 ; i < root.listFiles().length; i++) {
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File file = root.listFiles()[i];
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saveTree(file, level + 1 , node, session);
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}
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}
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}
60.
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public void printTree( long id) {
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Session session = null ;
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try {
64.
session = HibernateSessionFactory.getSession();
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Node node = (Node) session.load(Node. class , id);
66.
printNode(node);
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} catch (Exception e) {
68.
e.printStackTrace();
69.
} finally {
70.
HibernateSessionFactory.closeSession();
71.
}
72.
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}
74.
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public void printNode(Node node) {
76.
StringBuffer space = new StringBuffer();
77.
if (node.getLevel() != 0 ) {
78.
for ( int i = 0 ; i < node.getLevel(); i++) {
79.
space.append( " " );
80.
}
81.
space.append( "|_" );
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}
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System.out.println(space + node.getName());
84.
if (node.getChildren() != null && node.getChildren().size() != 0 ) {
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for (Iterator<Node> iterator = node.getChildren().iterator(); iterator.hasNext();) {
86.
Node nodeChild = iterator.next();
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printNode(nodeChild);
88.
}
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}
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}
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}
TestNode.java:
01.
package cn.edu.ahau.mgc.hibernate.export;
02.
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public class TestNode {
04.
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public static void main(String[] args) {
06.
NodeManager.getInstance().createTree( "E:/CODE/J2EE/Hibernate/hibernateTree" );
07.
NodeManager.getInstance().printTree( 1 );
08.
}
09.
}
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