Refresh token and reuse this token to get new access token java - google-drive-api

Question

How do I get the refresh token and the access token from the first time authorization code? And, how do I reuse this refresh token to get a new access token to upload to Google Drive using the Java API? This is not a web application. It's in Java Swing code.

Answer 1

We can reuse the refresh token to get new access token by following code
public class OAuthRefreshToken implements CredentialRefreshListener {
public static GoogleCredential getAccessTokenFromRefreshToken( String refreshToken, HttpTransport transport, com.google.api.client.json.JsonFactory jsonFactory, String CLIENT_ID, String CLIENT_SECRET) throws IOException
{
GoogleCredential.Builder credentialBuilder = new GoogleCredential.Builder()
.setTransport(transport).setJsonFactory(jsonFactory)
.setClientSecrets(CLIENT_ID, CLIENT_SECRET);
credentialBuilder.addRefreshListener(new OAuthRefreshToken());
GoogleCredential credential = credentialBuilder.build();
credential.setRefreshToken(refreshToken);
credential.refreshToken();
return credential;
}
#Override
public void onTokenErrorResponse(Credential arg0, TokenErrorResponse arg1)
throws IOException {
// TODO Auto-generated method stub
System.out.println("Error occured !");
System.out.println(arg1.getError());
}
#Override
public void onTokenResponse(Credential arg0, TokenResponse arg1)
throws IOException {
// TODO Auto-generated method stub
System.out.println(arg0.getAccessToken());
System.out.println(arg0.getRefreshToken());
}
}

Answer 2

Here is a solution I recently made up from the basic example in the Google Drive docs and some experimenting:
The IApiKey contains the static strings CLIENT_ID, and so on. ITokenPersistence is an interface which allows to load and save a token (as String). It decouples the persistence mechanism (I used Preferences for an Eclipse e4 RCP application) from the Uploader. This can be as simple as storing the token in a file The IAthorizationManager is an interface which is is used to let the user grant acces and enter the code to create the refresh token. I implemented a Dialog containing a browser widget to grant access and a text box to copy and paste the code to. The custom exception GoogleDriveException hides the API classes from the rest of the code.
public final class Uploader implements IApiKey {
public static final String TEXT_PLAIN = "text/plain";
private final ITokenPersistence tokenManager;
private final IAuthorizationManager auth;
public Uploader(final ITokenPersistence tm, final IAuthorizationManager am) {
this.tokenManager = tm;
this.auth = am;
}
private GoogleCredential createCredentialWithRefreshToken(
final HttpTransport transport,
final JsonFactory jsonFactory,
final String clientId,
final String clientSecret,
final TokenResponse tokenResponse) {
return new GoogleCredential.Builder().setTransport(transport)
.setJsonFactory(jsonFactory)
.setClientSecrets(clientId, clientSecret)
.build()
.setFromTokenResponse(tokenResponse);
}
/**
* Upload the given file to Google Drive.
* <P>
* The name in Google Drive will be the same as the file name.
* #param fileContent a file of type text/plain
* #param description a description for the file in Google Drive
* #return Answer the ID of the uploaded file in Google Drive.
* Answer <code>null</code> if the upload failed.
* #throws IOException
* #throws {#link GoogleDriveException} when a <code>TokenResponseException</code> had been
* intercepted while inserting (uploading) the file.
*/
public String upload(final java.io.File fileContent, final String description) throws IOException, GoogleDriveException {
HttpTransport httpTransport = new NetHttpTransport();
JsonFactory jsonFactory = new JacksonFactory();
// If we do not already have a refresh token a flow is created to get a refresh token.
// To get the token the user has to visit a web site and enter the code afterwards
// The refresh token is saved and may be reused.
final GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
httpTransport,
jsonFactory,
CLIENT_ID,
CLIENT_SECRET,
Arrays.asList(DriveScopes.DRIVE))
.setAccessType("offline")
.setApprovalPrompt("auto").build();
final String url = flow.newAuthorizationUrl().setRedirectUri(REDIRECT_URI).build();
final String refreshToken = this.tokenManager.loadRefreshToken();
GoogleCredential credential = null;
if( refreshToken == null ) {
// no token available: get one
String code = this.auth.authorize(url);
GoogleTokenResponse response = flow.newTokenRequest(code).setRedirectUri(REDIRECT_URI).execute();
this.tokenManager.saveRefreshToken(response.getRefreshToken());
credential = this.createCredentialWithRefreshToken(httpTransport, jsonFactory, CLIENT_ID, CLIENT_SECRET, response);
}
else {
// we have a token, if it is expired or revoked by the user the service call (see below) may fail
credential = new GoogleCredential.Builder()
.setJsonFactory(jsonFactory)
.setTransport(httpTransport)
.setClientSecrets(CLIENT_ID, CLIENT_SECRET)
.build();
credential.setRefreshToken(refreshToken);
}
//Create a new authorized API client
final Drive service = new Drive.Builder(httpTransport, jsonFactory, credential)
.setApplicationName(APP_NAME)
.build();
//Insert a file
final File body = new File();
body.setTitle(fileContent.getName());
body.setDescription(description);
body.setMimeType(TEXT_PLAIN);
final FileContent mediaContent = new FileContent(TEXT_PLAIN, fileContent);
try {
final File file = service.files().insert(body, mediaContent).execute();
return ( file != null ) ? file.getId() : null;
} catch (TokenResponseException e) {
e.printStackTrace();
throw new GoogleDriveException(e.getDetails().getErrorDescription(), e.getCause());
}
}
}