dwr+ext一棵树的问题

最近做了一棵树,可是点击时却无限制的加载,请各位大虾帮忙看下:

//设置树的点击事件
function treeClick(node,e) {
if(node.leaf){
e.stopEvent();
var tabs = tab.getComponent(node.id);
if (!tabs) {
tabs = tab.add({
'id' : node.id,
'title' : node.text,
closable:true,
html : '我是"'+node.text+'"'
});
}
tab.setActiveTab(tabs);
}
}

//生成标签页
var tab = new Ext.TabPanel({
region:'center',
deferredRender:false,
activeTab:0, 
resizeTabs:true, // turn on tab resizing
minTabWidth: 115,
tabWidth:135,
enableDD:true,
enableTabScroll:true,
    defaults: {frame:true, width:395, height: 300},
items:[{
                 title:'公告信息',
                 colspan:2,
                 autoScroll:true,
                 collapsible:true,
                 width:700,
                 height:500,
                 contentEl:'afficheDiv'
             }]
});

Ext.onReady(function(){
   //layout
   var viewport = new Ext.Viewport({
layout:'border',
items:[
new Ext.BoxComponent({
region:'south',
el: 'south',
height:25
}),{
region:'west',
id:'west-panel',
split:true,
width: 200,
minSize: 175,
maxSize: 400,
margins:'0 0 0 0',
layout:'accordion',
title:'系统菜单',
collapsible :true,
layoutConfig:{
animate:true
},
    items: [
    {
title:'EXT控件使用',
border:false,
html:'<div id="tree-div" style="overflow:auto;width:100%;height:100%"></div>'
//iconCls:'nav'
    },{
title:'信息中心',
border:false,
//iconCls:'settings',
html:'<div id="tree" style="overflow:auto;width:100%;height:100%"></div>'
    },{
title:'系统设置',
border:false,
//iconCls:'settings',
html:'<div id="tree3" style="overflow:auto;width:100%;height:100%"></div>'
    }]
},
        tab//初始标签页
]
});

//设置树形面板
var Tree = Ext.tree;
// set the root node
var root = new Tree.AsyncTreeNode({
text: '设置树形面板',
draggable:false,
id:'root'
});

var tree = new Tree.TreePanel({
el:'tree-div',
autoScroll:true,
root:root,
animate:true,
enableDD:false,
border:false,
rootVisible:false,
containerScroll: true,
loader: new Tree.TreeLoader({
dataUrl:'treedata.hr'
})
});

    tree.setRootNode(root);
// render the tree
tree.render();
root.expand();
tree.on('click',treeClick);

//end loding
setTimeout(
function() {
Ext.get('loading').remove();
Ext.get('loading-mask').fadeOut({remove:true});
}, 250
  );
});