Extjs 动态树

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/ext-base.js"></script>
<script type="text/javascript" src="js/ext-all.js"></script>
<link rel="stylesheet" type="text/css" href="css/ext-all.css"/>
<script type="text/javascript" >
    Ext.onReady(function() {
      alert("fdafd1");
     var  loader = new Ext.tree.TreeLoader({
           url : 'Tree?TID=100'
      });
    var Tree = Ext.tree;
var root = new Tree.AsyncTreeNode( {
text : '组织机构树',
draggable : false,
id : '-100'//默认的node值：?node=-100
});
var tree = new Ext.tree.TreePanel( {
el : 'tree-div',//目标div容器
autoScroll : true,
animate : true,
enableDD : true,
containerScroll : true,
loader : loader
});
   tree.setRootNode(root);   
      tree.on('beforeload', 
     function(node){ 
      tree.loader.dataUrl='Tree?TID='+node.id; //定义子节点的Loader 
     });    
tree.render();
root.expand();
tree.render('tree-div');
    tree.getRootNode().expand();

}); 
</script>
</head>
<body>
<%= request.getAttribute("aaa") %>
<div id="tree-div" style="overflow:auto; height:300px;width:200px;border:2px solid #c3daf9;"></div>
<form action="Tree" method="get">
 <input type="submit" name="安大叔大叔"/>
</form>
</body>
</html>
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/**
 * Servlet implementation class for Servlet: Tree
 *
 */
 public class Tree extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
   static final long serialVersionUID = 1L;
   
    /* (non-Java-doc)
 * @see javax.servlet.http.HttpServlet#HttpServlet()
 */
public Tree() {
super();
}   

/* (non-Java-doc)
 * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stubs
System.out.println("-----------------------------");
request.setAttribute("aaa", "bbb");
}  

/* (non-Java-doc)
 * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}           
}
<servlet>
    <description></description>
    <display-name>Tree</display-name>
    <servlet-name>Tree</servlet-name>
    <servlet-class>com.xiaoguo.servlet.Tree</servlet-class>
  </servlet>