Extjs4 简单的Tree panel树例子

//tree//treeExt.define('MyTreeModel', {    extend: 'Ext.data.Model',    fields: [ 'name','url' ]});var tree = Ext.create('Ext.tree.Panel',{    width:'200',    height:'200',    renderTo:'tree_div',    displayField:'name',    model:'MyTreeModel',    root:{        name:'根节点',        children:[            {name:'node1',url:'url1',leaf:true},            {name:'node2',url:'url2',leaf:true}        ]    }});