使用来自Java和Oauth 2.0的Google Calendar API：“权限不足”错误

Question

I have an application in whick an user can login with google. Than the user during his experience into the application can choose to integrate also the GoogleCalendar service. In order to achieve this my actual system works like the follow:

-when the user log in with google the system store his access and refresh token and calls Google to retrive basic profile information. In order to do that I create a GoogleCalendar object using the following call:

GoogleTokenResponse response = flow.newTokenRequest(code).setRedirectUri(GOOGLE_CALLBACK_URI).execute();
    GoogleCredential credential= new GoogleCredential.Builder().setJsonFactory(Constants.JSON_FACTORY)
            .setTransport(Constants.HTTP_TRANSPORT).setClientSecrets(Constants.GOOGLE_CLIENT_ID, Constants.GOOGLE_CLIENT_SECRET).build();
    credential.setAccessToken(response.getAccessToken());
    credential.setRefreshToken(response.getRefreshToken());    

-When the user choose to integrate the calendar service another Oauth iteration starts and the with a new code. I ask the GoogleCredential like before and access the service.

-When the systems need to perform some operations accessing Google Calendar I create a GoogleCredential object with the following call:

GoogleCredential c= new GoogleCredential.Builder().setJsonFactory(Constants.JSON_FACTORY)
            .setTransport(Constants.HTTP_TRANSPORT).setClientSecrets(Constants.GOOGLE_CLIENT_ID, Constants.GOOGLE_CLIENT_SECRET).build()
            .setAccessToken(user.getAccessToken()).setRefreshToken(user.getRefreshToken());    

Ans then ask for the service. But in this last case I get an error reporting 403 code and "Insufficient Permission" message.

I have checked that the stored access and refresh token I set into the GoogleCredential are the same I receive the first time getting the GoogleCredential with the "code". I also search a lot online but no solution would work. I'm really blocked into this error. Thank you in advance for the help and sorry if I miss specifing something or if I make some mistake in asking the question.

Answer 1

If I understand the problem you're describing correctly, incremental authorization may be what you're looking for: https://developers.google.com/accounts/docs/OAuth2WebServer#incrementalAuth

Specifically, add include_granted_scopes=true to your authorization URLs which should cause the resulting tokens to include the sum of all so-far-granted authorizations.