flex Menubar 单节点事件怎么加

Question

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        backgroundColor="#FFFFFF"  themeColor="#6699FF"  layout="vertical">
        <mx:Script>        
                        public function add():void
                        {
                                
                        }
        </mx:Script>
        <mx:MenuBar id="myMenuBar" labelField="@label" click="">
        <mx:XMLList>
            <menuitem label="添加" url=".../1.swf"/>   
            <menuitem label="导入" url=".../2.swf"/>
            <menuitem label="查询" url=".../3.swf"/>            
        </mx:XMLList>
        </mx:MenuBar>        
</mx:Application>单击一项，怎么获取url？