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用java小程序applet实现无限级树结构

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该程序可以根据从指定的xml文件中读取的有关信息动态的建立一棵树。

1.该树的特点:

1)无限级树结构

理论上树的深度可以无限,树的深度由xml文件所给的信息确定;

数据加载采用一次加载和动态加载相结合的方法;

每次打开相关页时重新加载树结构,真正的做到了建立树的动态性。

2)复用性

由于这棵树是通过读取xml文件建立的,树的程序代码固定,所以具有很强的复用性。只需要给出xml文件,程序就可以建立对应的树。

3)与用户的交互

由于该程序是用java小程序实现的,所以可以利用java语言中监听事件的类,以响应用户操作。与用户具有更好的交互性。

2.程序结构

这棵树主要有三个类实现:

1) 类TreeNode:该类起辅助作用,用来描述树的数据结构,并提供一些setter,getter函数用来设置树结构的属性。

2) 类IconRender:该类也是一个辅助类,用来设置树节点的图标。并且可以根据树节点的选中状态改变图标。

3) 类AppletTree:该类是建立这棵树的主要类,它继承自Applet并且实现了TreeSelectionListener接口,以用来监听用户操作。树结构由java类JTree显示,我们只需要合理的设定JTree的属性就可以构造出这棵树。而它的属性是通过jdom中的Element读取xml文件提供的。上面已经提到监听用户操作是通过实现TreeSelectionListener接口完成的,但是只监听不响应毫无用处。怎样才能将监听到的用户操作传给相应的类以响应用户的操作呢?这里用的方法是通过URL将参数传递给jsp文件,再由jsp文件传给相应的操作类实现的。

这三个类的代码如下:

1.TreeNode类

public class TreeNode{

private String id;

private String name;

private String link;

public TreeNode(String id,String name,String link){

this.id=id;

this.name=name;

this.link=link;

}

public String getId(){

return id;

}

public void setId(String Id){

this.id=Id;

}

public void setName(String Name){

this.name=Name;

}



public String getName(){

return name;

}



public String toString(){

return name;

}

public String getLink(){

return link;

}

public void setLink(String link){

this.link=link;

}

}

2. IconRender类

import javax.swing.*;

import java.awt.*;

import javax.swing.tree.*;

import javax.swing.tree.DefaultTreeCellRenderer;

IconRender

class extends DefaultTreeCellRenderer {





//创建用于显示的图标

public static final ImageIcon leafSelectedIcon = new ImageIcon("OpenedFolder.ico");

public static final ImageIcon leafUnSelectedIcon = new ImageIcon("closedFolder.ico");

public static final ImageIcon folderOpen = new ImageIcon("OpenedFolder.ico");

public static final ImageIcon folderClose = new ImageIcon("closedFolder.ico");



//设定图标随选中状态的变化

public Component getTreeCellRendererComponent(JTree

tree,Object value,boolean selected,boolean expanded,

boolean leaf, int row,boolean hasFocus)

{

super.getTreeCellRendererComponent(tree,value, selected, expanded, leaf, row, hasFocus);



if (leaf && selected) {

setIcon(IconRender.leafSelectedIcon);

}

else if (leaf) {

setIcon(IconRender.leafUnSelectedIcon);

}



return this;

}



public IconRender() {

super();

if((leafSelectedIcon != null)&&(leafUnSelectedIcon != null))

System.out.println("IconRender:trace");



setLeafIcon(leafUnSelectedIcon);

setOpenIcon(folderOpen);

setClosedIcon(folderClose);



}



}

3.AppletTree类

import javax.swing.event.*;

import java.awt.*;

import java.applet.*;

import javax.swing.*;

import javax.swing.tree.*;

import java.awt.event.*;

import org.jdom.*;

//import org.w3c.dom.NodeList;

import org.jdom.input.*;

import java.io.*;

import java.util.*;

import java.net.*;



import java.awt.*;

import javax.swing.*;

import javax.swing.border.*;

import javax.swing.plaf.*;

import javax.swing.plaf.basic.*;

import javax.swing.plaf.metal.*;







import java.io.*;

//import netscape.javascript.*;

class MyWindowListener extends WindowAdapter

{

public void windowClosing(WindowEvent e)

{

System.exit(1);

}

}



public class AppletTree extends Applet implements TreeSelectionListener

{

private JTree tree;



private TreePath path;

private JScrollPane treeView;

private DefaultMutableTreeNode top;



private DefaultMutableTreeNode clicknode;







private String link;



public AppletTree(){

}

MouseListener ml = new MouseAdapter() {

public void mousePressed(MouseEvent e) {

int selRow = tree.getRowForLocation(e.getX(), e.getY());

TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());

if(selRow != -1) {

if(e.getClickCount() == 1) {

System.out.print("点击一次鼠标");



//得到最后一个节点

DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode)selPath.getLastPathComponent();

boolean isLeaf = treeNode.isLeaf();



TreeNode objTreeNode = (TreeNode)treeNode.getUserObject();

System.out.println(isLeaf);

System.out.println(objTreeNode .getName()) ;

System.out.println(objTreeNode .getId()) ;

if(isLeaf)

{//如果为叶子节点就传出去进行查询操作

try

{

getAppletContext().showDocument(new URL("http://127.0.0.1:8080/tree/showDevice.htm"),"f2" );

}

catch(Exception ex)

{

System.out.print(ex);

}

}



}

else if(e.getClickCount() == 2) {

System.out.print("点击两次鼠标");

//getAppletContext().showDocument(new URL("http://www.csdn.net/"));

//myDoubleClick(selRow, selPath);

}

}

}

};





public void start()

{

super.start();

}



public void init(){

try{

super.init();

this.setLayout(new GridLayout(1,1));

tree=createTree(new FileInputStream("e:/example/TreeXML.xml"));

tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);

tree.putClientProperty("JTree.lineStyle","Angled");



tree.setShowsRootHandles(true);

tree.setEditable(true);

tree.addTreeSelectionListener( this );

IconRender render=new IconRender();

tree.setCellRenderer(render);





treeView = new JScrollPane(tree);

//topPanel.add(tree);

this.add(treeView);



tree.addMouseListener(ml);



}catch(Exception e){

e.printStackTrace();

}



}

public JTree createTree(InputStream is){

SAXBuilder builder = new SAXBuilder();

try {

Document doc = builder.build(is);

Element root=doc.getRootElement();

TreeNode rootNode=new

TreeNode(root.getAttributeValue("id"),root.getAttributeValue("name"),root.getAttributeValue("HaveChildren"));

top=new DefaultMutableTreeNode(rootNode);

addNode(root,top);

} catch (Exception ex) {

ex.printStackTrace();

}

//可以在这里改变jtree中连线的颜色

UIManager.put( "Tree.hash", new ColorUIResource(Color.red) );

return new JTree(top);



}



/**

*

* @param e 待加入树中的jdom元素

* @param fatherNode 树节点父亲节点

*/



private void addNode(Element e,DefaultMutableTreeNode fatherNode){

try{

Iterator it=e.getChildren().iterator();

if(!it.hasNext())

return;

while(it.hasNext()){



Element sub=(Element)it.next();



String id=new String(sub.getAttributeValue("id").getBytes(),"GB2312");

String name=new String(sub.getAttributeValue("name").getBytes(),"GB2312");

String link=new String(sub.getAttributeValue("HaveChildren").getBytes(),"GB2312");



System.out.println(id);

System.out.println(name);

System.out.println(link);



TreeNode tempNode=new TreeNode(id,name,link);



DefaultMutableTreeNode node=new DefaultMutableTreeNode(tempNode);

fatherNode.add(node);



if(link.equals("true")){

System.out.println("true~! equal test");

addNode(sub,node);

}

}

}

catch(Exception exp)

{

System.out.println("encoding fail");

}



}



/**

* 根据id,查找树节点,//广度优先

* @param id 节点id

* @param rootNode 树根节点

* @return DefaultMutableTreeNode

*/

private DefaultMutableTreeNode getTreeNode(String id,DefaultMutableTreeNode rootNode){

DefaultMutableTreeNode returnNode=null;

if(rootNode!=null){

Enumeration enum=rootNode.breadthFirstEnumeration();

while(enum.hasMoreElements()){

DefaultMutableTreeNode temp=(DefaultMutableTreeNode)enum.nextElement();

TreeNode node=(TreeNode)temp.getUserObject();

if(node.getId().equals(id)){

returnNode=temp;

break;

}

}

}

return returnNode;



}





public void valueChanged( TreeSelectionEvent event ){

if( event.getSource() == tree ){

path = event.getPath();

clicknode=(DefaultMutableTreeNode)path.getLastPathComponent();

Object uo=clicknode.getUserObject();

if(uo instanceof TreeNode){

TreeNode nd=(TreeNode)clicknode.getUserObject();

link=nd.getLink();

}

}

}





public static void main(String[] args ){

JFrame frame1=new JFrame("test");

AppletTree tree=new AppletTree();

tree.init();

frame1.getContentPane().add(tree);

frame1.setSize(600,600);



frame1.show();

frame1.addWindowListener(new MyWindowListener());

}



}





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