download-util.dart

class DownloadUtil {
  static Future<String> downloadAndSaveFile(String url, String fileName) async {
    final Directory directory = await getApplicationDocumentsDirectory();
    final String filePath = '${directory.path}/$fileName.png';
    final http.Response response = await http.get(Uri.parse(url));
    final File file = File(filePath);
    await file.writeAsBytes(response.bodyBytes);
    return filePath;
  }
}

Thanks for this