Java Requires Chilkat v10.1.2+

Get GMail SMTP OAuth2 Access Token for Desktop App

See more OAuth2 Examples

This example show how to obtain a Gmail SMTP OAuth2 access token from a desktop application or script, enabling the use of XOAUTH2 authentication. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.OAuth2;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        // To further clarify, see OAuth 2.0 Authorization Flow

        OAuth2 oauth2 = new OAuth2();

        // For Google OAuth2, set the listen port equal to the port used
        // in the Authorized Redirect URL for the Client ID.
        // For example, in this case the Authorized Redirect URL would be http://localhost:55568/
        // Your app should choose a port not likely not used by any other application.
        oauth2.setListenPort(55568);

        oauth2.setAuthorizationEndpoint("https://accounts.google.com/o/oauth2/v2/auth");
        oauth2.setTokenEndpoint("https://www.googleapis.com/oauth2/v4/token");

        // Replace these with actual values.
        oauth2.setClientId("GOOGLE-CLIENT-ID");
        oauth2.setClientSecret("GOOGLE-CLIENT-SECRET");

        // To use Gmail's OAuth2 for sending emails via the SMTP protocol, you need to request the https://mail.google.com/ scope.
        // See About GMail SMTP OAuth2 Scopes
        oauth2.setScope("https://mail.google.com/");

        // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
        String url;
        try {
            url = oauth2.startAuth();

            // Launch the default browser on the system and navigate to the url.
            // The LaunchBrowser method was added in Chilkat v10.1.2.
            oauth2.launchBrowser(url);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Wait for the user to approve or deny authorization in the browser.
        int numMsWaited = 0;
        while ((numMsWaited < 90000) && (oauth2.getAuthFlowState() < 3)) {
            oauth2.sleepMs(100);
            numMsWaited = numMsWaited + 100;
        }

        // If the browser does not respond within the specified time, AuthFlowState will be:
        //
        // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
        // 2: Waiting for Final Response – The thread is awaiting the final access token response.
        // In either case, cancel the background task initiated by StartAuth.

        if (oauth2.getAuthFlowState() < 3) {
            oauth2.cancel();
            System.out.println("No response from the browser!");
            return;
        }

        // Check AuthFlowState to determine if authorization was granted, denied, or failed:
        //
        // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
        // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
        // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

        if (oauth2.getAuthFlowState() == 5) {
            System.out.println("OAuth2 failed to complete.");
            System.out.println(oauth2.getFailureInfo());
            return;
        }

        if (oauth2.getAuthFlowState() == 4) {
            System.out.println("OAuth2 authorization was denied.");
            System.out.println(oauth2.getAccessTokenResponse());
            return;
        }

        if (oauth2.getAuthFlowState() != 3) {
            System.out.println("Unexpected AuthFlowState:" + oauth2.getAuthFlowState());
            return;
        }

        // Save the full JSON access token response to a file.
        StringBuilder sbJson = new StringBuilder();
        sbJson.append(oauth2.getAccessTokenResponse());
        sbJson.writeFile("qa_data/tokens/_gmailSmtp.json", "utf-8", false);

        // The saved JSON response looks like this:

        //     {
        //      "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
        //      "token_type": "Bearer",
        //      "expires_in": 3600,
        //      "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
        //     }
        //
        System.out.println("OAuth2 authorization granted!");
        System.out.println("Access Token = " + oauth2.getAccessToken());
    }
}