Flex中怎么给表格中的滚动条定位避免刷新回到原处

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