Send an HTTP Request with Oauth Authorisation (HMAC)

Hi guys, have asked this question on the new forum too but not really sure its up and kicking too much yet?

Basically i have have a sketch that uploads a file to my Wordpress site using an HTTP Post Request, the process uses basic access authentication (Basic Auth). Now i know this is not the most secure way of completing this so i would like to use OAuth 1 authorisation instead. I have everything setup in WordPress on the server side and have most of the required parameters, the only one that is proving a problem is the request HMAC-SHA1 signature. From what i have read i should be able to import a combo of Java libraries and make use of something similar to this code on github (first and last examples).

import java.security.SignatureException;
import java.util.Base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class HMAC_SHA1 {
    public static String Signature(String xData, String AppKey) throws java.security.SignatureException {
        try {
            final Base64.Encoder encoder = Base64.getEncoder();
            // get an hmac_sha1 key from the raw key bytes
            SecretKeySpec signingKey = new SecretKeySpec(AppKey.getBytes("UTF-8"),"HmacSHA1");

            // get an hmac_sha1 Mac instance and initialize with the signing key
            Mac mac = Mac.getInstance("HmacSHA1");
            mac.init(signingKey);

            // compute the hmac on input data bytes
            byte[] rawHmac = mac.doFinal(xData.getBytes("UTF-8"));
            String result = encoder.encodeToString(rawHmac);
            return result;

        } catch (Exception e) {
            throw new SignatureException("Failed to generate HMAC : "+ e.getMessage());
        }
    }
}

Only issue here is i cant figure out how to do that sadly. I have imported the required .jar files into my sketch and have copied over the code from github but after staring at it for ages i just cant figure out how i would use the HMAC_SHA1 class in my sketch with the variables/parameters i have already. I think i already have the xData and AppKey information if that makes any sense.

Any help would be really appreciated although i realise it’s a big ask, not your normal sort of processing thing.

Cheers