Flash 文件上传组件

朋友有个要求是要在页面上上传文件的时候只能选择指定类型(后缀名)的文件，显然是无能为力的(至少我没有找到办法，想来javascript/DOM也没有这种能力),所以考虑用Flash做一个小组件。
调用方式如下：

源代码如下：

	
			import mx.rpc.events.ResultEvent;
		import mx.collections.ArrayCollection;
	    import mx.controls.Alert;
		import mx.utils.ObjectUtil;
		import flash.events.*;
	    import flash.net.FileReference;
	    import flash.net.URLRequest;
	    import flash.net.FileFilter;
	    import com.adobe.serialization.json.JSON;

	    private var fileRef:FileReference;
	    private var sessionId:String;
	    private var fileFilter:Array;
	    private var uploadPath:String;


        private function initApp():void {
        	sessionId = Application.application.parameters.sessionId;
        	var ff:String = String(Application.application.parameters.fileFilter);
        	fileFilter = JSON.decode(ff) as Array;
        	uploadPath = Application.application.parameters.uploadPath;
            fileRef = new FileReference();
            fileRef.addEventListener(Event.CANCEL, traceEvent);
            fileRef.addEventListener(Event.COMPLETE, completeEvent);
            fileRef.addEventListener(Event.SELECT, selectEvent);
            fileRef.addEventListener(IOErrorEvent.IO_ERROR, traceEvent);
            fileRef.addEventListener(Event.OPEN, traceEvent);
            fileRef.addEventListener(ProgressEvent.PROGRESS, progressEvent);
            fileRef.addEventListener(SecurityErrorEvent.SECURITY_ERROR, traceEvent);
        }

		private function traceEvent(event:Event):void {
			//var tmp:String = "";
			//ta.text += tmp + event.type + " event:" + mx.utils.ObjectUtil.toString(event) + "\n" ;
			//ta.verticalScrollPosition += 20;
		}

		private function ioErrorEvent(event:IOErrorEvent):void{
			Alert.show("IOError:"+event.type+":" + event.text);
			traceEvent(event);
		}

		private function selectEvent(event:Event):void{
			btn_upload.enabled = true;
			traceEvent(event);
			filename.text = fileRef.name;
			progressBar.setProgress(0, 100);
			progressBar.label = "Loading 0%";			
		}

		private function progressEvent(event:ProgressEvent):void {
			progressBar.setProgress(event.bytesLoaded, event.bytesTotal);
			traceEvent(event);
		}

		private function completeEvent(event:Event):void {
			progressBar.label = "Complete.";
			filename.text += " uploaded";
			traceEvent(event);
			btn_upload.enabled = false;
			btn_cancel.enabled = false;			
		}

		private function uploadFile():void {
			var endpoint:String = uploadPath;
			endpoint += ";jsessionid="+sessionId;
			endpoint +="?fileType="+fileRef.type;
			var req:URLRequest = new URLRequest(endpoint);
			req.method = URLRequestMethod.POST;
			fileRef.upload(req, "filedata", false);
			progressBar.label = "Uploading...";		
			btn_cancel.enabled = true;
		}

		private function browseFile():void {
			var filters:Array = [];
			for(var i:int = 0; i < fileFilter.length; i++) {
				var filter:Object = fileFilter[i];
		        filters.push(new FileFilter(filter.name, filter.postFix));
			}
			fileRef.browse(filters);
		}
	]]>