google drive Oauth 2.0 for java web application - heroku

Question

My project is a java spark project that I have hosted on heroku. A part of the project requires that I download a particular file from my google drive into the application. I managed to set up everything when my application was running locally but as soon as I deployed the app it stopped working. This was regardless of the fact that when the app was running locally I used an Oauth2 client ID of type other and when I deployed the application I created a new one of type web application.
Below is a snippet of the authentication and download code:
public class AutoCalls {
/** Application name. */
private static final String APPLICATION_NAME = "calls-made";
private static final java.io.File DATA_STORE_DIR = new java.io.File(System.getProperty("target/classes/auth"), ".credentials/calls-made");
private static FileDataStoreFactory DATA_STORE_FACTORY;
private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
private static HttpTransport HTTP_TRANSPORT;
private static final List<String> SCOPES = Arrays.asList(DriveScopes.DRIVE);
static {
try {
HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
} catch (GeneralSecurityException | IOException t) {
System.exit(1);
}
}
public static void startDownload() throws IOException, ParseException {
Drive serv = getDriveService();
// drive stuff deleted
}
public static Credential authorize() throws IOException {
InputStream in = new FileInputStream("target/classes/auth/client_secret_*****************************************.apps.googleusercontent.com.json");
GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
.setDataStoreFactory(DATA_STORE_FACTORY)
.setAccessType("offline")
.build();
Credential credential = new AuthorizationCodeInstalledApp(flow, new LocalServerReceiver()).authorize("user");
System.out.println("Credentials saved to " + DATA_STORE_DIR.getAbsolutePath());
return credential;
}
public static Drive getDriveService() throws IOException {
Credential credential = authorize();
return new Drive.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential)
.setApplicationName(APPLICATION_NAME)
.build();
}
}
Currently when I try to initiate the download I get a URL in the Heroku logs a follows:
2017-02-20T10:32:28.656820+00:00 app[web.1]: Please open the following address in your browser:
2017-02-20T10:32:28.656908+00:00 app[web.1]: https://accounts.google.com/o/oauth2/auth?access_type=offline&client_id=************-vvdi7u6bmp1vc90sdidtnuiftdi1t49c.apps.googleusercontent.com&redirect_uri=http://localhost:48085/Callback&response_type=code&scope=https://www.googleapis.com/auth/drive
When I try open the URL in a browser I get an error:
Error: redirect_uri_mismatch
I cannot find any good step by step tutorial on accessing google drive contents on a java web application so any help would be arreiciated.

Answer 1

Generally, if OAuth works on server-A but not on server-B, it's because the redirect URL hasn't been configured correctly on the API Console. There is no reason why you would need to use a different client-ID because a single client-ID can be configured with multiple URLs, eg your local host and your heroku server. Another possibility is the use of https.
There is a separate problem in your code where you iterate on lista.isEmpty(). You should be iterating on nextPageToken != null. See the answer to Google drive rest API, Download files from root folder only