Java

Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time. Chilkat2 Java

import com.chilkatsoft.chilkat2.AuthGoogle;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.DateTime;
import com.chilkatsoft.chilkat2.FileAccess;
import com.chilkatsoft.chilkat2.Socket;

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.

        // First, let's get the current date/time from time-c.nist.gov
        Socket socket = new Socket();

        // Connect to an NIST time server and read the current date/time
        int maxWaitMs = 8000;
        boolean useTls = false;
        try {
            socket.connect("time-c.nist.gov", 37, useTls, maxWaitMs);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // The time server will send a big-endian 32-bit integer representing
        // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
        // The ReceiveInt32 method will receive a 4-byte integer, but returns
        // true or false to indicate success.  If successful, the integer
        // is obtained via the ReceivedInt property.
        boolean bigEndian = true;
        try {
            socket.receiveInt32(bigEndian);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        DateTime dt = new DateTime();
        dt.setFromNtpTime(socket.getReceivedInt());

        // Show the current local date/time
        boolean bLocalTime = true;
        System.out.println("Current local date/time: " + dt.getAsRfc822(bLocalTime));

        maxWaitMs = 10;
        socket.closeConnection(maxWaitMs);

        // ------------------------------------------------------------------------
        // OK, we have the current date/time.  We'll use it to set the IAT property
        // in the code below.

        // First load the JSON key into a string.
        FileAccess fac = new FileAccess();
        String jsonKey;
        try {
            jsonKey = fac.readEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // A JSON private key should look like this:

        //     {
        //       "type": "service_account",
        //       "project_id": "chilkattest-1350",
        //       "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
        //       "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
        //       "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
        //       "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
        //       "auth_uri": "https://accounts.google.com/o/oauth2/auth",
        //       "token_uri": "https://accounts.google.com/o/oauth2/token",
        //       "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
        //       "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
        //     }

        AuthGoogle gAuth = new AuthGoogle();
        gAuth.setJsonKey(jsonKey);

        // Choose a scope.
        gAuth.setScope("https://www.googleapis.com/auth/cloud-platform");

        // Request an access token that is valid for this many seconds.
        gAuth.setExpireNumSeconds(3600);

        // If the application is requesting delegated access:
        // The email address of the user for which the application is requesting delegated access,
        // then set the email address here. (Otherwise leave it empty.)
        gAuth.setSubEmailAddress("");

        // ------------------------------------------------------------------------
        // Set the IAT using the date/time from the NIST time server.
        int unixTime = (int) dt.getAsUnixTime(false);
        System.out.println("unixTime = " + unixTime);
        gAuth.setIat(unixTime);

        // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
        // The Chilkat socket object is used so that the connection can be established
        // through proxies or an SSH tunnel if desired.
        Socket tlsSock = new Socket();
        try {
            tlsSock.connect("www.googleapis.com", 443, true, 5000);

            // Send the request to obtain the access token.
            gAuth.obtainAccessToken(tlsSock);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Examine the access token:
        System.out.println("Access Token: " + gAuth.getAccessToken());
    }
}