How to insert integer/float as byte arrays into HBase with Stargate REST?

I know that Stargate expects the values to be inserted into a HBase table to be base64 encoded.

How do we base64 encode numerical values like integer and floats before forming the JSON payload for HTTP PUT?

I could solve this myself, below is the snippet how I could encode integer and double values:

long t = 11; 
String e1 = Base64.encodeBase64String(BigInteger.valueOf(t).toByteArray());

t = 78; 
String e2 = Base64.encodeBase64String(BigInteger.valueOf(t).toByteArray());     

System.out.println("e1: "+e1+", e2: "+e2);

try {
  ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
  DataOutputStream out = new DataOutputStream(byteOut);

  double d = -1.966723;
  out.writeDouble(d);
  out.flush();
  byte[] buf  = byteOut.toByteArray();
  String e3 = Base64.encodeBase64String(buf);   
  System.out.println("e3: "+e3);
}
catch(Exception e) {
    System.out.println("Exception: "+e);
}