How to open and PDF or word document in the [Flutter]

Question

Question is simple, I would like to open any pdf or doc file via default App with using Flutter.

Think a Raised button that related my pdf asset, when user press it

Answer 1

class EmployeeViewModel {
  EmployeeModel _employeeModel = EmployeeModel();

   String fname;   
                                                                                                                              void downloadFile(BuildContext context, String fileUrl, String fileName, ProgressListener listener) async {

    String _filePath = '';

    if (Platform.isAndroid) {
      String _directory = await ExtStorage.getExternalStoragePublicDirectory(ExtStorage.DIRECTORY_DOWNLOADS);
      print(_directory);
      _filePath = '$_directory/$fileName';
      //todo getting file name here
      print("file name" + fileName);
      fname = fileName;
      print("file fname" + fname);
      //APIKey.FILE_NAME: fileName;
    } else if (Platform.isIOS) {
      Directory _directory = await getApplicationDocumentsDirectory();
      _filePath = '${_directory.path}/$fileName';

      print("file name" + fileName);
      //log(fileName);
      debugPrint(_directory.path);
      print("directory path" + _directory.path);
    }

    var response = await Dio().downloadUri(Uri().resolve(fileUrl), _filePath);

    if (response.statusCode == 200) {
      listener.isProcessing(false);
      AlertMessageDialog(context,  UtilString.downloadCompleted, UtilString.downloadCompletedMessage, UtilString.open, AlertMessageDialogActionHandler());
    } else {
      listener.isProcessing(false);
      UtilAction.showSnackBar(context, response.statusMessage);
    }
  }                                                                                                  class AlertMessageDialogActionHandler implements AlertMessageDialogListener {

  @override
  Future onPositiveButtonClick() async {
    String _filePath = '';
    String fileName;
    String _directory = await ExtStorage.getExternalStoragePublicDirectory(ExtStorage.DIRECTORY_DOWNLOADS);
    //todo geeting right directory path here
    print("directory" + _directory);
    _filePath = '$_directory/$fileName';
    print("file path" + _filePath);
   // print("filename" + fileName);

    OpenFile.open("/storage/emulated/0/Download/GA55-Estimated-SHRIGOPAL-VERMA-2020-2021.pdf");  }}