flex对话框限制所显示的文件类型实例

<?xml version="1.0" encoding="utf-8"?> 
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" fontSize="16" layout="absolute">

    <mx:Script> 
        <![CDATA[
            import flash.events.Event;
			import flash.net.FileFilter;
			import flash.net.FileReference;
			import flash.net.FileReferenceList;

            private var fileRL:FileReferenceList;

            /**
            * 1、imgStr:String --- 是弹出对话框下面的"文件类型(T):"下拉框里面的值，可随便写
            * 2、str:String --- 是列出的在弹出框主面板上显示的这些指定类型的文件
            **/
            private function showWindow(imgStr:String, str:String):void{
            	fileRL = new FileReferenceList();
                fileRL.browse([new FileFilter(imgStr, str)]); 
                fileRL.addEventListener(Event.SELECT, onFileSelect); 
            }            

            private function onFileSelect(event:Event):void{ 
                for(var i:int = 0; i < fileRL.fileList.length; i++){ 
                   var fr:FileReference = FileReference(fileRL.fileList[i]);  
                   textID.text = fr.name;                   
                }                
            }

        ]]>
    </mx:Script> 

    <mx:Button id="openButID" x="400" y="50" label="打开对话框"
    	 click="showWindow('Images (*.jpg, *.gif, *.png)', '*.jpg;*.gif;*.png');"/>

    <mx:Text id="textID" x="400" y="300" width="300"/>

</mx:Application>