flex datagrid获取每一行的值,该如何解决

flex datagrid获取每一行的值
各位什么，请问怎么调取datagrid中每一行的值？
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
   xmlns:s="library://ns.adobe.com/flex/spark" 
   xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" xmlns:ns="http://www.esri.com/2008/ags" xmlns:layout="flexlib.scheduling.scheduleClasses.layout.*" xmlns:local="*"
   initialize="application2_initializeHandler(event)">
<fx:Script>
<![CDATA[
import flash.profiler.showRedrawRegions;

import mx.collections.ArrayCollection;
import mx.collections.IList;
import mx.controls.Alert;
import mx.core.UIComponent;
import mx.events.FlexEvent;
import mx.events.ListEvent;

[Bindable]
public var arraycollection:ArrayCollection = new ArrayCollection([{name:"zhangsan",sex:"nan",nianling:5},
{name:"lisi",sex:"nan",nianling:6},
{name:"ru",sex:"nan",nianling:22},
{name:"dao",sex:"nv",nianling:23},
{name:"sao",sex:"nv",nianling:25}
]);

protected function application2_initializeHandler(event:FlexEvent):void
{
// TODO Auto-generated method stub

}
public function choose(event:ListEvent):void
{
var field:String = event.target.columns[event.columnIndex].dataField;
// Alert.show(field);
var s:String = String(event.target.dataProvider.getItemAt(event.rowIndex)[datagrid.columns[event.columnIndex]]);
Alert.show(s);
}

]]>
</fx:Script>
<fx:Declarations>

</fx:Declarations>
<s:Group  width="100%" height="100%">
<s:VGroup width="100%" height="100%">
<mx:DataGrid id="datagrid" dataProvider="{arraycollection}" width="100%" height="100%" itemClick="choose(event)">
<mx:columns>
<mx:DataGridColumn dataField="name" headerText="名字"/>
<mx:DataGridColumn dataField="sex" headerText="性别"/>
<mx:DataGridColumn dataField="nianling" headerText="年龄"/>
</mx:columns>
</mx:DataGrid>
</s:VGroup>
</s:Group>

</s:Application>
------解决思路----------------------
arraycollection.selectedItem    对选中项的引用
不知道你是要获取arraycollection所有值，还是只获取某一行的值
------解决思路----------------------
你这是要获取你点击的那一行的值，还是整个datagrid的值啊，要是一行的话，就是datagrid.selectItem.名称，要是整个的话，就用数据源不就行了吗