How to retreive raw post data from HttpServletRequest in java

public static String getPostData(HttpServletRequest req) {
    StringBuilder sb = new StringBuilder();
    try {
        BufferedReader reader = req.getReader();
        reader.mark(10000);

        String line;
        do {
            line = reader.readLine();
            sb.append(line).append("\n");
        } while (line != null);
        reader.reset();
        // do NOT close the reader here, or you won't be able to get the post data twice
    } catch(IOException e) {
        logger.warn("getPostData couldn't.. get the post data", e);  // This has happened if the request's reader is closed
    }

    return sb.toString();
}