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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