Java

Google Calendar -- Refresh an Expired Access Token

See more Google Calendar Examples

Demonstrates how to refresh an expired access token. If a Google Calendar REST API call results in a 401 "unauthorized" response, then it is likely the access token expired. An application should be able to automatically refresh the access token with no user interaction and then re-try the request with the newly obtained access token. Chilkat2 Java

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

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        // It is assumed we previously obtained an OAuth2 access token.
        // This example loads the JSON access token file
        // saved by this example: Get Google Calendar OAuth2 Access Token

        JsonObject jsonToken = new JsonObject();
        try {
            jsonToken.loadFile("qa_data/tokens/googleCalendar.json");
        } catch (ChilkatException e) {
            System.out.println("Failed to load googleCalendar.json");
            return;
        }

        // The access token JSON looks like this:

        //     {
        //      "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
        //      "token_type": "Bearer",
        //      "expires_in": 3600,
        //      "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
        //     }
        //

        OAuth2 oauth2 = new OAuth2();

        oauth2.setTokenEndpoint("https://www.googleapis.com/oauth2/v4/token");

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

        // Get the "refresh_token"
        oauth2.setRefreshToken(jsonToken.stringOf("refresh_token"));

        // Send the HTTP POST to refresh the access token..
        try {
            oauth2.refreshAccessToken();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // The response contains a new access token, but we must keep
        // our existing refresh token for when we need to refresh again in the future.
        jsonToken.updateString("access_token", oauth2.getAccessToken());

        // Save the new JSON access token response to a file.
        StringBuilder sbJson = new StringBuilder();
        jsonToken.setEmitCompact(false);
        jsonToken.emitSb(sbJson);
        sbJson.writeFile("qa_data/tokens/googleCalendar.json", "utf-8", false);

        System.out.println("OAuth2 authorization granted!");
        System.out.println("New Access Token = " + oauth2.getAccessToken());
    }
}