<? xml version = " 1.0 "  encoding = " utf-8 " ?>
< mx:Application xmlns:mx = " http://www.adobe.com/2006/mxml "
                layout = " vertical "
                creationComplete = " initApp() " >

< mx:Script >
<! [CDATA[

     //  On startup
     public  function initApp(): void
    {
         //  Set filter function
         //  Be careful to set filterFunction
         //  only after ArrayCollection has been
         //  populated.
        myData.filterFunction = processFilter;
    }

     //  Filter function
     public  function processFilter(item:Object):Boolean
    {
        var result:Boolean = false ;

         //  If no filter text, or a match, then true
         if  ( ! item.name.length
                 ||  item.name.toUpperCase().indexOf(txtFilter.text.toUpperCase())  >=   0 )
        result = true ;

         return  result;
    }
]] >
</ mx:Script >

<!--  Data (use ArrayCollection)  -->
< mx:ArrayCollection id = " myData " >
     < mx:source >
         < mx:Object name = " Ben Forta "
            location = " Oak Park, MI "
            phone = " (248)555-5555 "   />
         < mx:Object name = " Jane Doe "
            location = " New York, NY "
            phone = " (212)555-1234 "   />
         < mx:Object name = " Jim Jones "
            location = " Atlanta, GA "
            phone = " (414)555-1212 "   />
         < mx:Object name = " Roberta Roberts "
            location = " Chicago, IL "
            phone = " (312)555-4321 "   />
         < mx:Object name = " Steve Stevens "
            location = " Boston, MA "
            phone = " (617)555-5656 "   />
     </ mx:source >
</ mx:ArrayCollection >

<!--  UI  -->
< mx:HBox width = " 100% " >
     < mx:Label text = " Filter: " />
     < mx:TextInput id = " txtFilter "
            width = " 100% "
            change = " myData.refresh() " />
</ mx:HBox >

< mx:DataGrid dataProvider = " {myData} "
        width = " 100% "  height = " 100% " >
     < mx:columns >
         < mx:DataGridColumn headerText = " Name "
                    dataField = " name " />
         < mx:DataGridColumn headerText = " Location "
                    dataField = " location " />
         < mx:DataGridColumn headerText = " Phone "             dataField = " phone " />
     </ mx:columns >
</ mx:DataGrid >
</ mx:Application >

其中主要的是ArrayCollection的filterFunction属性,他的使用方法如下:
ArrayCollection的filterFunction属性是继承自ListCollectionView的，还有其他类具有这个功能,以下是一个继承关系图,详细的可以看flex 的帮助文件
filterFunction属性的值是一个函数(Function)：
参数：Object类型的一个值,也可以不带参数；
返回值：Boolean类型的值，如果返回值为True就把这个Object放到里面,反之亦然。
其函数格式事例如下：
f(item:Object):Boolean
在函数里面进行处理,以上的例子就是如此：
 public function processFilter(item:Object):Boolean
 {
       var result:Boolean=false;
      // 查看文本框里的字符串长度或字符串的匹配（大小写都可以），然后返回结果。
      if (!item.name.length || item.name.toUpperCase().indexOf(txtFilter.text.toUpperCase()) >= 0)
     result=true;
     return result;
 }
注意：filterFunction函数只有在对象建立的时候和调用reflash()的时候执行的，所以一定要在显示之前调用下reflash()，否则显示就不正常了，切记！切记！