Download file in Dart/Flutter

download.dart

static var httpClient = new HttpClient();
Future<File> _downloadFile(String url, String filename) async {
  var request = await httpClient.getUrl(Uri.parse(url));
  var response = await request.close();
  var bytes = await consolidateHttpClientResponseBytes(response);
  String dir = (await getApplicationDocumentsDirectory()).path;
  File file = new File('$dir/$filename');
  await file.writeAsBytes(bytes);
  return file;
}

Future saveLocalFile(BuildContext context, String localFilePath) async {
try {
showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return Center(
child: CircularProgressIndicator(),
);
},
);

  String filePath = localFilePath; 

  File file = File(filePath);
  if (await file.exists()) {
    Directory? appDocDir = await getExternalStorageDirectory();
    if (appDocDir != null) {
      String destPath = "${appDocDir.path}/${file.path.split('/').last}";

      await file.copy(destPath);

      String mimeType = _getMimeType(destPath);

      if (Platform.isAndroid) {
        final androidFile = File(destPath);
        await androidFile.writeAsBytes(await file.readAsBytes(),
            flush: true);
        await androidFile.uri;
      }

      Navigator.pop(context); 
      showMessage('File saved successfully', Colors.green);
    } else {
      throw 'Failed to get directory for saving file';
    }
  } else {
    throw 'File not found at path: $filePath';
  }
} catch (e) {
  Navigator.pop(context);
  showMessage('Failed to save file: $e', Colors.red);
}

}

file downloading but not opening , please give me a solution