@Path("/gdrive")
public class GDrive {

   private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
   private static final List<String> SCOPES = Arrays.asList(DriveScopes.DRIVE_READONLY);

   @GET
   @Path("/start")
   public void start(@Context HttpServletRequest request, @Context HttpServletResponse response) throws IOException {

       InputStream in = GDrive.class.getResourceAsStream("/client_secret.json");
       GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

       GoogleAuthorizationCodeRequestUrl flow = new GoogleAuthorizationCodeRequestUrl( clientSecrets,
                                                                                    "http://localhost:8080/GDriveRest/app/gdrive/finish",
                                                                                    SCOPES);
       flow.put("access-type", "offline");
       flow.put("include_granted_scopes", "true");

       response.sendRedirect(flow.toString());
   }

   @GET
   @Path("/finish")
   public void finish(@Context HttpServletRequest request, @Context HttpServletResponse response) throws IOException {

       if (request.getParameter("code") != null) {
           response.sendRedirect("http://m.memegen.com/1yx6o5.jpg?"+request.getParameter("code"));
       }
       else {
           response.sendRedirect("https://img.memecdn.com/wat-error_c_1405685.jpg");
       }
   }
}