Template:Json API HMAC Block- Java

public static void generateHmacHeaders(HttpURLConnection connection) throws Exception {

   final SimpleDateFormat d = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss (z)"); // Create the date string
   d.setTimeZone(TimeZone.getTimeZone("GMT"));
   final String timestampString = d.format(new Date());

   final String message = applicationId + ":" + applicationPassword + ":" + timestampString;// Create the message

   final String auth = "HMAC " + hmacSha1ToBase64(message, apiSecret); // Create the authorization hash

   connection.setRequestProperty("updox-timestamp", timestampString);  // Set the request headers
   connection.setRequestProperty("Authorization", auth);

}

public static String hmacSha1ToBase64(String value, String key) throws Exception{

   byte[] keyBytes = key.getBytes();// Get an hmac_sha1 key from the raw key bytes
   SecretKeySpec signingKey = new SecretKeySpec(keyBytes, "HmacSHA1");

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

   byte[] rawHmac = mac.doFinal(value.getBytes());// Compute the hmac on input data bytes

   byte[] base64Bytes = Base64.encodeBase64(rawHmac);// Convert raw bytes to Hex

   return new String(base64Bytes, "UTF-8");// Covert array of Hex bytes to a String

}