Flutter Web 下载文件在移动浏览器中不起作用

如何解决Flutter Web 下载文件在移动浏览器中不起作用

我正在创建Flutter web，用于下载图像。下载或保存功能仅在桌面功能。移动浏览器无法下载或保存图片。

这是我的代码：

未来的 getWidgetimage() 异步 {

try {
  RenderRepaintBoundary boundary =
      globalKey.currentContext.findRenderObject();
  ui.Image image = await boundary.toImage(pixelRatio: 3.0);
  ByteData byteData =
   await image.toByteData(format: ui.ImageByteFormat.png);
  var pngBytes = byteData.buffer.asUint8List();
  var bs64 = base64Encode(pngBytes);
  debugPrint(bs64.length.toString());
  print("convert done");

  imageList.add(pngBytes);

 if (kIsWeb) {
    websaveAndLaunchFile(bytes,qrName+'.png');
       } 
     else {
     mobilesaveAndLaunchFile(bytes,qrName+'.png');
       }
    return pngBytes;
 } catch (exception) {
  return null;
 }
}

//websave 包

Future <void> websaveAndLaunchFile (List<int> bytes,String fileName)async {
       
    AnchorElement(
    href: "data:application/octet- 
    stream;charset=ut16le;base64,${base64.encode(bytes)}")
    ..setAttribute("Download",fileName)
    ..click();
 }

//移动保存包

Future<void> mobilesaveAndLaunchFile(List<int> bytes,String fileName)async{

   final path = ( await getExternalStorageDirectory()).path;
   final file = File('$path/$fileName');
   await file.writeAsBytes(bytes,flush: true);
   OpenFile.open('$path/$fileName');
}