Helper methods

Helper.java

private Map<String, String> parseRequestHeaders(BufferedReader in) throws IOException {
    Map<String, String> headers = new HashMap<>();
    // parse the first line.
    String header = in.readLine();
    StringTokenizer tokenizer = new StringTokenizer(header);
    headers.put(METHOD, tokenizer.nextToken().toUpperCase());
    headers.put(RESOURCE, tokenizer.nextToken().toLowerCase());
    headers.put(PROTOCOL, tokenizer.nextToken());
    // Rest of the headers
    String line;
    while ((line = in.readLine()) != null && !line.isEmpty()) {
        int idx = line.indexOf(':');
        if (idx > 0) {
            headers.put(line.substring(0, idx).toLowerCase(), line.substring(idx + 1).trim());
        }
    }
    return headers;
}
private OutputStream getDataOutputStream(Map<String, String> requestHeaders, OutputStream outputStream)
        throws IOException {
    String acceptedEncoding = requestHeaders.getOrDefault(Http.Header.ACCEPT_ENCODING, "");
    if (acceptedEncoding.contains("gzip")) {
        return new GZIPOutputStream(outputStream);
    }
    return new BufferedOutputStream(outputStream);
}

private String getContentEncoding(Map<String, String> requestHeaders) {
    String acceptedEncoding = requestHeaders.getOrDefault(Http.Header.ACCEPT_ENCODING, "");
    return acceptedEncoding.contains(GZIP) ? GZIP : null;
}
private void writeResponseHeaders(PrintWriter out, String protocol, String status, String mimeType, String date,
                                  int length, String contentEncoding) {
    out.println(protocol + status);
    out.println(SERVER + config.getProperty(SERVER_VERSION_PARAM));
    out.println(DATE + date);
    if (contentEncoding != null)
        out.println(CONTENT_ENCODING + contentEncoding);
    out.println(CONTENT_TYPE + mimeType + ";charset=\"utf-8\"");
    out.println(CONTENT_LENGTH + length);
    out.println(CONNECTION + "close");
    out.println();
    out.flush();
}