=========== test2.html =================
[html]
[head]
  [link rel="stylesheet" type="text/css" href="../resources/css/ext-all.css"]
 [script type="text/javascript" src="../adapter/ext/ext-base.js"][/script]
 [script type="text/javascript" src="../ext-all.js"][/script]
    [script type="text/javascript" src="reorder2.js"][/script]
[title]Insert title here[/title]
[/head]
[body]
[div id="tree-div" style="overflow:auto; height:300px;width:250px;border:1px solid #c3daf9;"][/div]
[/body]
[/html]
=============== reorder2.js ====================
Ext.onReady(function(){
    // shorthand
    var Tree = Ext.tree;    
    var tree = new Tree.TreePanel({
        el:'tree-div',
        useArrows:true,
        autoScroll:true,
        animate:true,
        enableDD:true,
//  rootVisible: false,
        containerScroll: true, 
        loader: new Tree.TreeLoader({
   dataUrl:'json.jsp'
        })
    });
    // set the root node
    var root = new Tree.AsyncTreeNode({
        text: 'Ext JS',
        draggable:false,
  iconCls:'conthruAr',
        id:'source'
    });
    tree.setRootNode(root);
    // render the tree
    tree.render();
    root.expand();
});
================ json.jsp =================
[%@page import="java.util.Enumeration"%]
[%
 Enumeration ss = request.getParameterNames();
 String value;
 while(ss.hasMoreElements()){
  String key = (String)ss.nextElement();
  value = request.getParameter(key);
  System.out.println(key+" : "+value+" ");
 } 
 String getS = request.getParameter("node"); 
 System.out.println("ss : "+getS);
 if (getS.equals("source")){
%]
[{"text":"1","id":"1","cls":"folder"},{"text":"4","id":"4","leaf":true,"cls":"file"},{"text":"3","id":"3","cls":"folder"},{"text":"2","id":"2","leaf":true,"cls":"file"}]
[%
 } else if(getS.equals("3")) {
%]
[{"text":"7","id":"7","leaf":true,"cls":"file"},{"text":"8","id":"8","cls":"folder"}]
[%} %]