How to authenticate Google Drive without requiring the user to copy/paste auth code?

Question

I'm playing around with the DriveCommandLine applicaiton to learn the Drive API a bit. I'm just wondering if it is possible to authenticate my desktop application with Google Drive without the user needing to copy/paste an auth code from the browser? But rather just have a token passed back to the app from the browser? I am able to do this with Dropbox API and with the Google Documents List API, but cannot figure out how to get this working with the Google Drive API.

Thanks.

Google Drive API - DriveCommandLine sample app (slightly modified):

public class DriveCommandLine {

  private static String CLIENT_ID = APPCONSTANTS.Google.CONSUMER_KEY;
  private static String CLIENT_SECRET = APPCONSTANTS.Google.CONSUMER_SECRET;

  private static String REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob";

  public static void main(String[] args) throws IOException, URISyntaxException {
    HttpTransport httpTransport = new NetHttpTransport();
    JsonFactory jsonFactory = new JacksonFactory();

    GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
        httpTransport, jsonFactory, CLIENT_ID, CLIENT_SECRET, Arrays.asList(DriveScopes.DRIVE))
        .setAccessType("offline")
        .setApprovalPrompt("force").build();

    String url = flow.newAuthorizationUrl().setRedirectUri(REDIRECT_URI).build();
    System.out.println("Enter authorization code:");
    Desktop.getDesktop().browse(new URI(url));
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String code = br.readLine();

    GoogleTokenResponse response = flow.newTokenRequest(code).setRedirectUri(REDIRECT_URI).execute();
    GoogleCredential credential = new GoogleCredential().setFromTokenResponse(response);

    //Create a new authorized API client
    Drive service = new Drive.Builder(httpTransport, jsonFactory, credential).build();
}

Google Documents List API:

    public void authenticate(){
            GoogleOAuthParameters oauthParameters = new GoogleOAuthParameters();
            oauthParameters.setOAuthConsumerKey(APPCONSTANTS.Google.CONSUMER_KEY);

            OAuthSigner signer;
            if (APPCONSTANTS.Google.USE_RSA_SIGNING) {
                    signer = new OAuthRsaSha1Signer(APPCONSTANTS.Google.CONSUMER_SECRET);
            } else {
                oauthParameters.setOAuthConsumerSecret(APPCONSTANTS.Google.CONSUMER_SECRET);
                signer = new OAuthHmacSha1Signer();
            }

            GoogleOAuthHelper oauthHelper = new GoogleOAuthHelper(signer);

            oauthParameters.setScope(APPCONSTANTS.Google.SCOPES);

            oauthHelper.getUnauthorizedRequestToken(oauthParameters);

            String requestUrl = oauthHelper.createUserAuthorizationUrl(oauthParameters);

            Desktop desktop = Desktop.getDesktop();
            URI url = new URI(requestUrl);
            desktop.browse(url);

            String token = oauthHelper.getAccessToken(oauthParameters);
    }

Answer 1

The command line samples were written for simplicity, not necessarily the best user experience. In this case, they're running as local apps and are using the installed app flow for OAuth 2.0. That flow does have a mode where the redirect_uri can point to localhost, but it requires starting up a temporary web server to receive the redirect. Rather than complicate the sample, it uses the OOB mode which requires copy/pasting the code.

If you're building a desktop app, I'd encourage going the route of redirecting to localhost as it is a better UX.

See https://developers.google.com/accounts/docs/OAuth2InstalledApp for more info.

Answer 2

Step 1: Generate the URL using offline access type

flow = new GoogleAuthorizationCodeFlow.Builder(
httpTransport, jsonFactory, CLIENT_ID, CLIENT_SECRET, Arrays.asList(DriveScopes.DRIVE))
.setAccessType("offline")
.setApprovalPrompt("auto").build();
String url = flow.newAuthorizationUrl().setRedirectUri(REDIRECT_URI).build();

Step 2: Store the credentials accessToken and refreshToken

GoogleTokenResponse response = flow.newTokenRequest(code).setRedirectUri(REDIRECT_URI).execute();
            GoogleCredential credential = new GoogleCredential.Builder().setTransport(httpTransport)
                .setJsonFactory(jsonFactory)
                .setClientSecrets(CLIENT_ID, CLIENT_SECRET)
                .build()
                .setFromTokenResponse(response);
String accessToken = credential.getAccessToken();
String refreshToken = credential.getRefreshToken();

Step 3: Reuse tokens when needed

GoogleCredential credential1 = new GoogleCredential.Builder().setJsonFactory(jsonFactory)
.setTransport(httpTransport).setClientSecrets(CLIENT_ID, CLIENT_SECRET).build();
credential1.setAccessToken(accessToken);
credential1.setRefreshToken(refreshToken);
Drive service = new Drive.Builder(httpTransport, jsonFactory, credential1).build();

Step 4: Understand OAuth to handle errors and refreshing of the tokens