How do I control Token Response Expiry time for google API access - google-api

Question

I have problem extending the standard one hour for validity of google access token.
One part of my code is getting authorization from the user, using the GoogleAuthorizationCodeFlow as per Google recommendation. This works fine and gives me a TokenResponse that I persist to be used in an other part of the application where the user is not connected.
As per Google documentation, I thought that the "offline" access type in the flow would enable the TokenResponse to be usable as longer as the user doesnt revoke it. But apparently when I use this TokenReponse just after the user authorization, it works fine but when I use it after more than one hour, I get an "invalid credentials" sent back by Google.
Here is the code which creates the TokenResponse once the user has authorized it :
private HttpTransport HTTP_TRANSPORT;
private JacksonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
private static GoogleAuthorizationCodeFlow flow;
#PostConstruct
public void init() {
try {
HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
} catch (GeneralSecurityException | IOException e) {
logger.info(String.format("Raised Exception while getting GoogleNetHttpTransport : %s", e.getMessage()));
e.printStackTrace();
}
flow = new GoogleAuthorizationCodeFlow.Builder(HTTP_TRANSPORT, JSON_FACTORY, APP_ID, APP_SECRET,
Collections.singleton(CalendarScopes.CALENDAR_READONLY)).setAccessType("offline").build();
}
#RequestMapping(value = Uris.GOOGLERD)
public ModelAndView googleCallBack(HttpServletRequest request, #RequestParam(value = "state", required = false) String state,
#RequestParam(value = "code", required = false) String code,
#RequestParam(value = "error", required = false) String error, Model model) {
DynSubscriber dynSubscriber = (DynSubscriber) request.getSession().getAttribute("dynSubscriber");
ModelAndView toReturn = new ModelAndView("confirmation");
toReturn.addObject("buttonLabel", "Accueil");
try {
AuthorizationCodeTokenRequest tokenRequest = flow.newTokenRequest(code);
TokenResponse tr = tokenRequest.setRedirectUri(request.getRequestURL().toString()).execute();
// Json Conversion of Token Response for future use
StringWriter jsonTrWriter = new StringWriter();
JsonGenerator generator = JSON_FACTORY.createJsonGenerator(jsonTrWriter);
generator.serialize(tr);
generator.flush();
generator.close();
//Persists google access info
dynSubOp.setSPConnexionInfo(dynSubscriber, jsonTrWriter.toString(), DynServiceProviderType.GOOGLECAL);
toReturn.addObject("message","Agenda Google autorisé");
} catch (IOException | DynServicesException e) {
logger.error(String.format("Exception raised in googleCallBack for subscriber %s : %s", dynSubscriber.buildFullName(), e.getMessage()),e);
toReturn.addObject("message", "Problème lors du processus d'autorisation google");
}
return toReturn;
}
}
And here is the offline code which uses this TokenReponse :
private com.google.api.services.calendar.Calendar calendarConnection;
public DynGoogleCalendarRetriever(String subid, String connectionInformation)
throws CalendarConnectionNotAuthorizedException {
TokenResponse tr;
try {
HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
tr = JSON_FACTORY.fromString(connectionInformation, TokenResponse.class);
Credential c = new GoogleCredential().setFromTokenResponse(tr);
calendarConnection = new com.google.api.services.calendar.Calendar.Builder(HTTP_TRANSPORT, JSON_FACTORY, c)
.build();
} catch (IOException | GeneralSecurityException e) {
logger.error(String.format("Failure creating the credentials for subscriber id %s", subid), e);
throw new CalendarConnectionNotAuthorizedException(String.format(
"Failure creating the credentials for subscriber id %s", subid), e);
}
}

Answer 1

Looks like this was already answered in this other SO question.
To get the refresh token that enables what I want, I need to build the flow with a approval_prompt=force parameter (builder.setApprovalPrompt("force"))
As per the comment, this requires the offline access which is done in the flow initialization.
A complement however : the offline code in my question doesn't work as such although I copied and pasted it from google documentation (probably an older version). The Credential needs to use its Builder object.
Here is the fully functionnal offline code :
TokenResponse tr;
try {
HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
tr = JSON_FACTORY.fromString(connectionInformation, TokenResponse.class);
Credential c = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT).setJsonFactory(JSON_FACTORY)
.setClientSecrets(APP_ID, APP_SECRET).build().setFromTokenResponse(tr);
calendarConnection = new com.google.api.services.calendar.Calendar.Builder(HTTP_TRANSPORT, JSON_FACTORY, c)
.build();
} catch (IOException | GeneralSecurityException e) {
logger.error(String.format("Failure creating the credentials for subscriber id %s", subid), e);
throw new CalendarConnectionNotAuthorizedException(String.format(
"Failure creating the credentials for subscriber id %s", subid), e);
}