How to get google access token from serverAuthCode in Java?

Question

I am using https://github.com/react-native-google-signin/google-signin ,in my UI from here i have got serveAuthCode, But i am not able to figure out how get accesstoken from this serverAuthCode in java backend. Any help would be greatly appreciated.

Answer 1

similar issue : link

in my case i was getting serverAuthCode from https://github.com/react-native-google-signin/google-signin,

in the backend then you can do below code

import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeTokenRequest;
import com.google.api.client.googleapis.auth.oauth2.GoogleTokenResponse;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;

    public static final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();
    public static final JsonFactory JSON_FACTORY = new JacksonFactory();
GoogleTokenResponse response = new GoogleAuthorizationCodeTokenRequest(Auth.HTTP_TRANSPORT, Auth.JSON_FACTORY,
 Your_OAUTH_CLIENTID, 
Your_OAUTH_CLIENTSECRET, 
Serverauthcode_from_react_native, "")
.execute();

//below code gets you access token of longer expiration date

GoogleCredential refreshTokenCredential = new GoogleCredential.Builder()
                        .setJsonFactory(Auth.JSON_FACTORY)
                        .setTransport(Auth.HTTP_TRANSPORT)
                        .setClientSecrets(Your_OAUTH_CLIENTID, Your_OAUTH_CLIENTSECRET)
                        .build()
                        .setRefreshToken(response.getRefreshToken());
                refreshTokenCredential.refreshToken(); 
String newAccessToken = refreshTokenCredential.getAccessToken();

Note: The serverAuthCode can be used only once , from the response that you get you should store the refreshToken, and from next time use refreshToken to get you AccessToken