Invalid grant when authenticating to Google

Question

I'm trying to connect to the Google Calendar API. I am have followed the step in Google calendar quick start for Java

{ "error" : "invalid_grant", "error_description" : "Bad Request" }

Can you please advise on how to debug this? The error message is unfortunately not helpful and I already tried everything I could find about this particular error on Stack overflow or elsewhere

Every time I got the same access token for different credentials:

Access token: {user=Class{accessToken=null, refreshToken="" expirationTimeMilliseconds=null}}

code:

public class CalendarServiceImpl implements CalendarService {

    public static final String APPLICATION_NAME = "GoogleCalenderApi";
    public static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    public static final String TOKENS_DIRECTORY_PATH = "/data.json";
    public static final List<String> SCOPES = Collections.singletonList(CalendarScopes.CALENDAR);
    public static final String CREDENTIALS_FILE_PATH = "/data.json";

    public Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT, HttpServletRequest request)
            throws IOException {

        InputStream in = CalendarServiceImpl.class.getResourceAsStream(CREDENTIALS_FILE_PATH);

        if (in == null) {
            log.info("Resource not found: " + CREDENTIALS_FILE_PATH);
            throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
        }

        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
        GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(HTTP_TRANSPORT, JSON_FACTORY,
                clientSecrets, SCOPES)
                        .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
                        .setAccessType("offline")
                        .build();

        System.out.println("Access token: " + flow.getCredentialDataStore());

        LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(80)
                .build();


        return new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
    }

    public void createCalendarEvent(String candidateMailId, String companyEmailId, DateTime fromTime, DateTime toTime,
            String summary, String description, HttpServletRequest request)
            throws GeneralSecurityException, IOException {
        final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();

        Event event = new Event().setSummary(summary).setLocation("Test").setDescription(description);

        EventDateTime start = new EventDateTime().setDateTime(fromTime).setTimeZone("Asia/Kolkata");
        event.setStart(start);

        EventDateTime end = new EventDateTime().setDateTime(toTime).setTimeZone("Asia/Kolkata");
        event.setEnd(end);

        String[] recurrence = new String[] { "RRULE:FREQ=DAILY" };
        event.setRecurrence(Arrays.asList(recurrence));

        EventAttendee[] attendees = new EventAttendee[] { new EventAttendee().setEmail(candidateMailId),
                new EventAttendee().setEmail(companyEmailId) };
        event.setAttendees(Arrays.asList(attendees));

        EventReminder[] reminderOverrides = new EventReminder[] { new EventReminder().setMethod("email").setMinutes(10),
                new EventReminder().setMethod("popup").setMinutes(10), };
        Event.Reminders reminders = new Event.Reminders().setUseDefault(false)
                .setOverrides(Arrays.asList(reminderOverrides));
        event.setReminders(reminders);


        // Build service account credential.
        Credential credential = getCredentials(HTTP_TRANSPORT, request);
        log.info("got  credential:" + event);

        Calendar service = new Calendar.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME).build();


        String calendarId = "primary";
        try {
            System.out.printf("Event started" + event);
            event = service.events().insert(calendarId, event).setSendUpdates("all").execute();
        } catch (IOException e) {
            log.info("event  IOException:" + e);
            e.getMessage();
        }
        log.info("Event created:" + event.getHtmlLink());

    }

}

Answer 1

You appear to be using AuthorizationCodeInstalledApp which as it stats is for installed applications. for web applications you need to use AuthorizationCodeFlow.

The official example can be found here Web server application

public class CalendarServletSample extends AbstractAuthorizationCodeServlet {

  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException {
    // do stuff
  }

  @Override
  protected String getRedirectUri(HttpServletRequest req) throws ServletException, IOException {
    GenericUrl url = new GenericUrl(req.getRequestURL().toString());
    url.setRawPath("/oauth2callback");
    return url.build();
  }

  @Override
  protected AuthorizationCodeFlow initializeFlow() throws IOException {
    return new GoogleAuthorizationCodeFlow.Builder(
        new NetHttpTransport(), JacksonFactory.getDefaultInstance(),
        "[[ENTER YOUR CLIENT ID]]", "[[ENTER YOUR CLIENT SECRET]]",
        Collections.singleton(CalendarScopes.CALENDAR)).setDataStoreFactory(
        DATA_STORE_FACTORY).setAccessType("offline").build();
  }

  @Override
  protected String getUserId(HttpServletRequest req) throws ServletException, IOException {
    // return user ID
  }
}

public class CalendarServletCallbackSample extends AbstractAuthorizationCodeCallbackServlet {

  @Override
  protected void onSuccess(HttpServletRequest req, HttpServletResponse resp, Credential credential)
      throws ServletException, IOException {
    resp.sendRedirect("/");
  }

  @Override
  protected void onError(
      HttpServletRequest req, HttpServletResponse resp, AuthorizationCodeResponseUrl errorResponse)
      throws ServletException, IOException {
    // handle error
  }

  @Override
  protected String getRedirectUri(HttpServletRequest req) throws ServletException, IOException {
    GenericUrl url = new GenericUrl(req.getRequestURL().toString());
    url.setRawPath("/oauth2callback");
    return url.build();
  }

  @Override
  protected AuthorizationCodeFlow initializeFlow() throws IOException {
    return new GoogleAuthorizationCodeFlow.Builder(
        new NetHttpTransport(), JacksonFactory.getDefaultInstance()
        "[[ENTER YOUR CLIENT ID]]", "[[ENTER YOUR CLIENT SECRET]]",
        Collections.singleton(CalendarScopes.CALENDAR)).setDataStoreFactory(
        DATA_STORE_FACTORY).setAccessType("offline").build();
  }

  @Override
  protected String getUserId(HttpServletRequest req) throws ServletException, IOException {
    // return user ID
  }
}

AuthorizationCodeFlow opens the consent browser window in the machine that the code is running on. When you are running something as a website it needs to open on the client machine so that the user can see it.