How to store credentials for Google Drive SDK locally

Question

I am developing a Java based desktop application which needs to download some files from the user's Google Drive account. I have studied the Google Drive SDK documentation and so far I have come up with the following code:

public class Main
{
  public static void main(String[] args)
  {
    String clientId = "...";
    String clientSecret = "...";

    HttpTransport httpTransport = new NetHttpTransport();
    JsonFactory jsonFactory = new JacksonFactory();

    GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
      httpTransport, 
      jsonFactory,
      clientId,
      clientSecret,
      Arrays.asList(DriveScopes.DRIVE)
    )
      .setAccessType("online")
      .setApprovalPrompt("auto").build();

    String redirectUri = "urn:ietf:wg:oauth:2.0:oob";     
    String url = 
      flow
        .newAuthorizationUrl()
        .setRedirectUri(redirectUri)
        .build();

    System.out.println("Please open the following URL in your browser then type the authorization code:");
    System.out.println("  " + url);
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String code = br.readLine();

    GoogleTokenResponse response = 
      flow
        .newTokenRequest(code)
        .setRedirectUri(redirectUri)
        .execute();

    GoogleCredential credential = 
      new GoogleCredential()
        .setFromTokenResponse(response);

    Drive service = 
      new Drive.Builder(httpTransport, jsonFactory, credential)
        .build();

    ...
  }
}

This works but it requires the user to authorize the application (i.e. open the given URL in a browser and copy the authorization token) each time. I need to implement the application in a way that would require the user to authorize it when he runs it for the first time only. The application would then store some kind of a secret token locally to be used the next time.

I have studied the documentation thoroughly but I haven't found any sufficient explanation about how to achieve this goal (in a desktop application particularly).

How do I do that?

score 3 · Answer 1 · answered Dec 09 '14 at 09:07

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 . code = response code for above url

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

score 0 · Accepted Answer · answered Sep 14 '13 at 15:11

0

At http://javadoc.google-api-java-client.googlecode.com/hg/1.7.0-beta/jdiff/Google%20API%20Client%20Library%20for%20Java%201.7.0-beta/com/google/api/client/googleapis/auth/oauth2/GoogleAuthorizationCodeFlow.html read about accessType = "offline". This will return a Refresh Token, which is the storable "secret token" that you're looking for. Save this and you can convert it to an Auth Token without any user intervention.

answered Sep 14 '13 at 15:11

pinoyyid

21,499
14
64
115

Could you please be more specific about how do I update the code? I cannot seem to get it working. Thanks in advance! – Dušan Rychnovský Sep 14 '13 at 15:44
add .setAccessType("offline") in your flow...build. There is an example here http://stackoverflow.com/questions/10294124/getting-null-refresh-token . Alternatively you could just call the URLs directly as described here https://developers.google.com/accounts/docs/OAuth2InstalledApp – pinoyyid Sep 14 '13 at 16:06
And why would you have the user open a browser url and copy the token? Why not urlfetch it? – Zig Mandel Sep 14 '13 at 16:32
@ZigMandel I don't understand what you mean by urlfetching the token. Could you please explain it? – Dušan Rychnovský Sep 14 '13 at 17:42
See the google oauth docs on client type flow. There are examples there. – Zig Mandel Sep 15 '13 at 03:45

How to store credentials for Google Drive SDK locally

2 Answers2

Linked