Flex中怎么给表格中的滚动条定位

1、问题背景

       如果表格中的字段过多，会出现滚动条，在将滚动条滚到一定的位置时，重新刷新表格，滚动条会回到原处，原来查看的字段还得继续滚动，才能查看到。

2、实现实例

<?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"
   creationComplete="initHandler(event)"
   width="100%" height="100%">
<s:layout>
<s:BasicLayout/>
</s:layout>
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.controls.Alert;
import mx.events.FlexEvent;

[Bindable]
//表格数据绑定
private var gridArray:ArrayCollection = new ArrayCollection([
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
 Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"},
{Jan:"5678",Feb:"7890",Mar:"3454",Apr:"4565",May:"6756",Jun:"5656",Jul:"7867",Aug:"8990",Sep:"5676",Oct:"4655",Nov:"6778",Dec:"8909",
Jan1:"3344",Feb1:"5676",Mar1:"7898",Apr1:"9089",May1:"9009",Jun1:"5675",Jul1:"3433",Aug1:"4455",Sep1:"6676",Oct1:"7867",Nov1:"4556",Dec1:"8656"}
]);

/**
 * 初始化函数
 */
protected function initHandler(event:FlexEvent):void
{

}

/**
 * 刷新按钮函数
 */
protected function refresh_clickHandler(event:MouseEvent):void
{
var hx:Object = hsb.left;
var hy:Number = hsb.y;

//var dx:Number = dataGrid.contentMouseX;
//var dy:Number = dataGrid.contentMouseY;
//Alert.show("hx："+hx+"\n"+"hy: "+hy + "\n" + "dx: " + dx + "\n" + "dy: " + dy);
Alert.show("hx："+hx+"\n"+"hy: "+hy);
}

]]>
</fx:Script>
<fx:Declarations>
<!-- 将非可视元素（例如服务、值对象）放在此处 -->
</fx:Declarations>

<mx:VBox width="100%" height="100%" paddingBottom="10" paddingLeft="10" paddingRight="20" 
 paddingTop="10" horizontalAlign="center">
<mx:HBox width="100%" height="30">
<s:Label width="100%"/>
<s:Button id="refresh" label="刷新" click="refresh_clickHandler(event)"/>
</mx:HBox>
<mx:DataGrid width="1350" height="90%" id="dataGrid" dataProvider="{gridArray}" horizontalScrollPolicy="on" textAlign="center">
<mx:columns>
<mx:DataGridColumn headerText="2013年01月" dataField="Jan" width="200"/>
<mx:DataGridColumn headerText="2013年02月" dataField="Feb" width="200"/>
<mx:DataGridColumn headerText="2013年03月" dataField="Mar" width="200"/>
<mx:DataGridColumn headerText="2013年04月" dataField="Apr" width="200"/>
<mx:DataGridColumn headerText="2013年05月" dataField="May" width="200"/>
<mx:DataGridColumn headerText="2013年06月" dataField="Jun" width="200"/>
<mx:DataGridColumn headerText="2013年07月" dataField="Jul" width="200"/>
<mx:DataGridColumn headerText="2013年08月" dataField="Aug" width="200"/>
<mx:DataGridColumn headerText="2013年09月" dataField="Sep" width="200"/>
<mx:DataGridColumn headerText="2013年10月" dataField="Oct" width="200"/>
<mx:DataGridColumn headerText="2013年11月" dataField="Nov" width="200"/>
<mx:DataGridColumn headerText="2013年12月" dataField="Dec" width="200"/>
<mx:DataGridColumn headerText="2014年01月" dataField="Jan1" width="200"/>
<mx:DataGridColumn headerText="2014年02月" dataField="Feb1" width="200"/>
<mx:DataGridColumn headerText="2014年03月" dataField="Mar1" width="200"/>
<mx:DataGridColumn headerText="2014年04月" dataField="Apr1" width="200"/>
<mx:DataGridColumn headerText="2014年05月" dataField="May1" width="200"/>
<mx:DataGridColumn headerText="2014年06月" dataField="Jun1" width="200"/>
<mx:DataGridColumn headerText="2014年07月" dataField="Jul1" width="200"/>
<mx:DataGridColumn headerText="2014年08月" dataField="Aug1" width="200"/>
<mx:DataGridColumn headerText="2014年09月" dataField="Sep1" width="200"/>
<mx:DataGridColumn headerText="2014年10月" dataField="Oct1" width="200"/>
<mx:DataGridColumn headerText="2014年11月" dataField="Nov1" width="200"/>
<mx:DataGridColumn headerText="2014年12月" dataField="Dec1" width="200"/>
</mx:columns>
</mx:DataGrid>
<!--
<s:HScrollBar id="hsb" width="100%" viewport="{dataGrid}"/>
-->

<s:HScrollBar id="hsb" width="100%"/>

</mx:VBox>
</s:Application>

3、实现结果