AS3 / AIR：尝试上载文件时出现IOStream错误

Question

我正在创建一个AIR应用程序，用户将图像文件拖放到舞台上，然后应用程序将这些已删除的图像上传到网站imgur.com，然后返回图像链接（XML格式）。

我有两个问题：

该程序使用一个非常小的文件成功运行，但是任何更大的（1mb或更多），我得到一个iostream错误2023.Imgur支持高达10mb的上传，所以我知道它必须是我的结果。
我希望能够一次将多个图像文件放入程序中，并将其全部上传（同步或异步，无关紧要）。现在，当我尝试执行此操作时程序会出错（byteArray的行必须大于0）。

以下是有问题的代码，它给我提出了问题。（谢谢你的高级帮助）

private function doDragDrop(e:NativeDragEvent):void
{           
    trace("doDragDrop() called.");
    var dropFiles:Array = e.clipboard.getData(ClipboardFormats.FILE_LIST_FORMAT) as Array;
    for each (var file:File in dropFiles)
    {
        switch (file.extension.toLowerCase())
        {
            case "jpg" :
            case "jpeg" :
            case "gif" :
            case "png" :
            case "apng" :
            case "tiff" :
            case "bmp" :
            case "pdf" :
            case "xcf" :
            trace("file Extension Check = passed");
            addImage(file.nativePath);
                break;

            //error handling for non-supported filetypes
            default :
                trace("ERROR: Unsupported File Type Detected!");
        }
    }
}

private function addImage(nativePath:String):void
{
    trace("addImage() called.");
    trace("NativePath is: " + nativePath);
    //var file:File = new File(nativePath);
    var file:File = File.desktopDirectory.resolvePath(nativePath);
    var ba:ByteArray = new ByteArray();
    var stream:FileStream = new FileStream();
    stream.open(file, FileMode.READ);
    stream.readBytes(ba);
    stream.close();         
    var loader:Loader = new Loader();
    loader.contentLoaderInfo.addEventListener(Event.COMPLETE, fileLoaded);
    loader.loadBytes(ba);
}

private function fileLoaded(e:Event):void
{
    trace("fileLoaded() called.");
    var bitmap:Bitmap = Bitmap(e.target.content);
    var bitmapData:BitmapData = bitmap.bitmapData;
    var png:ByteArray = PNGEncoder.encode(bitmapData);

    urlLoader = new URLLoader();
    urlLoader.dataFormat = URLLoaderDataFormat.VARIABLES;
    urlLoader.addEventListener(Event.COMPLETE, onCookieSent);
    urlLoader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, onSecurityError);
    urlLoader.addEventListener(IOErrorEvent.IO_ERROR, onIOError);

    var vars:String = "?key=" + API_KEY + "&name=name&title=title";
    var request:URLRequest = new URLRequest(UPLOAD_URL + vars);
    request.contentType = "application/octet-stream";
    request.method = URLRequestMethod.POST;
    request.data = png;
    urlLoader.load(request);
}

private function onCookieSent(e:Event):void
{
    trace("onCookieSent() called.");
    var res:XML = new XML(unescape(urlLoader.data));
    var resultsList:XMLList = res.links;
    trace(resultsList);
}

private function onIOError(e:IOErrorEvent):void 
{
    trace("ioErrorHandler: " + e);
    TweenLite.to(tv_mc, 2, {alpha:0.5, scaleX:1.0, scaleY:1.0, ease:Elastic.easeOut});
    // Handle error
}
private function onSecurityError(e:SecurityErrorEvent):void 
{
    trace("securityErrorHandler: " + e);
    TweenLite.to(tv_mc, 2, {alpha:0.5, scaleX:1.0, scaleY:1.0, ease:Elastic.easeOut});
    // handle error
}

//When the dragged object leaves the drop point, do this
private function doDragExit(e:NativeDragEvent):void
{
    trace("doDragExit() called.");
    TweenLite.to(tv_mc, 2, {alpha:0.5, scaleX:1.0, scaleY:1.0, ease:Elastic.easeOut});
}