Ext.tree.TreeLoader怎么运用

Ext.onReady(function(){

var loader=new Ext.tree.TreeLoader({
url:"treedata.js"
});
var root=new Ext.tree.AsyncTreeNode({
id:"root",
text:"根节点",
loader:loader});
var tree=new Ext.tree.TreePanel({
renderTo:"hello",
root:root,
width:100
});

});

你在后台生成store的时候加进去，
var store = Ext.create('Ext.data.TreeStore', {
root: {
expanded: true,
children: [
{ text: "detention", leaf: true },
{ text: "homework", expanded: true, children: [
{ text: "book report", leaf: true },
{ text: "alegrbra", leaf: true}
] },
{ text: "buy lottery tickets", leaf: true }
]
}
});

Ext.create('Ext.tree.Panel', {
title: 'Simple Tree',
width: 200,
height: 150,
store: store,
rootVisible: false,
renderTo: Ext.getBody()
});

loader: new Ext.tree.TreeLoader(),

就是加载个树