public static String strToBase36(String str) {

        String returnStr = "";
        if (StringUtil.isNullOrEmpty(str)) {
            return returnStr;
        }

        for (int i = 0; i < str.length(); i++) {
            int n = str.codePointAt(i);
            returnStr = returnStr + pad(intToBase36(n), 3, "0");
        }

        return returnStr;
    }