(Java) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

Chilkat Java Downloads Java Libs for Windows, MacOS, Linux, Alpine Linux, Solaris Java Libs for Android

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

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

    // We're going to duplicate this CURL statement:
    // curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
    // -H "Content-Type: application/x-www-form-urlencoded" \
    // -H "API-Key: xxxxxx" \
    // -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

    // Load our pre-creaed private key PEM file.
    // Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
    // Token generation will not work unless public key is associated with your app.
    CkPrivateKey privkey = new CkPrivateKey();

    boolean success = privkey.LoadPemFile("qa_data/pem/abnAmroPrivateKey.pem");
    if (success == false) {
        System.out.println(privkey.lastErrorText());
        return;
        }

    // Create the JWT.
    CkJwt jwt = new CkJwt();

    // Create the header:
    // {
    //     "typ": "JWT",
    //     "alg": "RS256"
    // }
    CkJsonObject jsonHeader = new CkJsonObject();
    jsonHeader.UpdateString("typ","JWT");
    jsonHeader.UpdateString("alg","RS256");

    // Create the payload:
    // {
    //     "nbf": 1499947668,
    //     "exp": 1499948668,
    //     "iss": "me",
    //     "sub": "anApiKey",
    //     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
    // }
    CkJsonObject jsonPayload = new CkJsonObject();

    int curDateTime = jwt.GenNumericDate(0);

    // Set the "not process before" timestamp to now.
    success = jsonPayload.AddIntAt(-1,"nbf",curDateTime);

    // Set the timestamp defining an expiration time (end time) for the token
    // to be now + 1 hour (3600 seconds)
    success = jsonPayload.AddIntAt(-1,"exp",curDateTime+3600);

    jsonPayload.UpdateString("iss","me");
    jsonPayload.UpdateString("sub","anApiKey");
    jsonPayload.UpdateString("aud","https://auth-sandbox.abnamro.com/oauth/token");

    // Produce the smallest possible JWT:
    jwt.put_AutoCompact(true);

    String jwtStr = jwt.createJwtPk(jsonHeader.emit(),jsonPayload.emit(),privkey);
    if (jwt.get_LastMethodSuccess() != true) {
        System.out.println(jwt.lastErrorText());
        return;
        }

    CkHttp http = new CkHttp();

    CkHttpRequest req = new CkHttpRequest();
    req.AddParam("client_assertion_type","urn:ietf:params:oauth:client-assertion-type:jwt-bearer");
    req.AddParam("grant_type","client_credentials");
    req.AddParam("client_assertion",jwtStr);
    req.AddParam("scope","tikkie");

    CkHttpResponse resp = http.PostUrlEncoded("https://api-sandbox.abnamro.com/v1/oauth/token",req);
    if (http.get_LastMethodSuccess() == false) {
        System.out.println(http.lastErrorText());
        return;
        }

    if (resp.get_StatusCode() != 200) {
        System.out.println(resp.bodyStr());

        return;
        }

    // Get the JSON result:
    // {
    //     "access_token": "{your access token}",
    //     "expires_in": "{duration of validity in seconds}",
    //     "scope": "{scope(s) for which the access token is valid}",
    //     "token_type": "{it is always Bearer}"
    // }
    CkJsonObject json = new CkJsonObject();
    json.Load(resp.bodyStr());
    System.out.println("access_token: " + json.stringOf("access_token"));
    System.out.println("token_type: " + json.stringOf("token_type"));
    System.out.println("expires_in: " + json.stringOf("expires_in"));
    System.out.println("scope: " + json.stringOf("scope"));
  }
}