(Java) Walmart Partner API Authentication (Generate a Signature for a Request)

Demonstrates how to generate a signature for a Walmart Partner REST API call.

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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.

    boolean success;

    String consumerId = "b68d2a72....";
    String baseUrl = "https://marketplace.walmartapis.com/v2/feeds";
    // This is your Base64 encoded private key
    String privateEncodedStr = "MIICeAIBADANBgkqhkiG9w0BAQEFAA......";
    String httpMethod = "GET";

    // We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
    CkDateTime dt = new CkDateTime();
    // Set bLocal = true for a timestamp in the local timezone.  Set bLocal = false for a UTC timestamp.
    boolean bLocal = false;
    // This gets the timestamp in seconds, not milliseconds.
    int timeStampVal = dt.GetAsUnixTime(bLocal);

    // Build the string to sign.
    CkStringBuilder sbStringToSign = new CkStringBuilder();
    sbStringToSign.Append(consumerId);
    sbStringToSign.Append("\n");
    sbStringToSign.Append(baseUrl);
    sbStringToSign.Append("\n");
    sbStringToSign.Append(httpMethod);
    sbStringToSign.Append("\n");
    sbStringToSign.AppendInt(timeStampVal);
    // We add three zero's so that the timestamp value is in milliseconds.
    // We don't care about accuracy down to less than a second.
    // All the server cares about is that the request was signed at the current date/time
    // within some reasonable margin of error (to account for systems having clocks
    // that may be slightly different).
    sbStringToSign.Append("000\n");

    CkPrivateKey privKey = new CkPrivateKey();
    // Load the private key into a private key object.
    // Note: Technically the private key is not PEM because it lacks the header/footer strings
    // used for PEM.  However, the LoadPem method will still accept it and load it correctly.
    success = privKey.LoadPem(privateEncodedStr);
    if (success != true) {
        System.out.println(privKey.lastErrorText());
        return;
        }

    CkRsa rsa = new CkRsa();
    success = rsa.ImportPrivateKeyObj(privKey);
    if (success != true) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    // We want a base64 signature string.
    rsa.put_EncodingMode("base64");

    String signatureString = rsa.signStringENC(sbStringToSign.getAsString(),"SHA256");
    if (rsa.get_LastMethodSuccess() != true) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    System.out.println("Signature String: " + signatureString);
  }
}