将xml数据填入Tree

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" creationComplete="application1_creationCompleteHandler()"
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600">
    <s:layout>
        <s:VerticalLayout horizontalAlign="center" verticalAlign="middle"/>
    </s:layout>
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;
            import mx.rpc.events.ResultEvent;
            [Bindable]
            private var d:XML;
            
            protected function httpservice1_resultHandler(event:ResultEvent):void
            {
                d=event.result as XML;
                trace(d);
                t.dataProvider=d;
                
            }
            
            protected function application1_creationCompleteHandler():void
            {
                http.send();
                
            }
            
        ]]>
    </fx:Script>
    <fx:Declarations>
        <!-- 将非可视元素（例如服务、值对象）放在此处 -->
        <s:HTTPService id="http" url="data/data.xml" resultFormat="e4x" result="httpservice1_resultHandler(event)" />
    </fx:Declarations>
    <mx:Tree id="t" labelField="@value" width="400" height="300"></mx:Tree>
</s:Application>