private HashMap<String, Integer> parseRange() {
        HashMap<String, Integer> rangeMap = new HashMap<>();
        Pattern pattern = Pattern.compile("((?<=\\nRange: bytes=)([^\\r]+))");
        Matcher matcher = pattern.matcher(headerString);
        if (matcher.find()) {
            String[] range = matcher.group(1).split("-");
            if (range.length == 2) {
                rangeMap.put("Begin", Integer.parseInt(range[0]));
                rangeMap.put("End",   Integer.parseInt(range[1]));
                int length = rangeMap.get("End") - rangeMap.get("Begin") + 1;
                rangeMap.put("Length", length);
            }
        }
        return rangeMap;
    }