download image in flutter

download_image.dart

  Future<dynamic> downloadImage() async {
    String dir = (await getApplicationDocumentsDirectory()).path;
    File file = new File('$dir/$filename');

    if (file.existsSync()) {
      print('file already exist');
      var image = await file.readAsBytes();
      return image;
    } else {
      print('file not found downloading from server');
      var request = await http.get(url,);
      var bytes = await request.bodyBytes;//close();
      await file.writeAsBytes(bytes);
      print(file.path);
      return bytes;
    }
  }