java 获取用户真实ip

/**
         * 获取用户真实ip
         * @param request
         * @return
         */
        public static String getIpAddr(HttpServletRequest request){
            String ip = request.getHeader("x-forwarded-for");
            if ((ip == null) || (ip.length() == 0) || ("unknown".equalsIgnoreCase(ip))) {
              ip = request.getHeader("Proxy-Client-IP");
            }
            if ((ip == null) || (ip.length() == 0) || ("unknown".equalsIgnoreCase(ip))) {
              ip = request.getHeader("WL-Proxy-Client-IP");
            }
            if ((ip == null) || (ip.length() == 0) || ("unknown".equalsIgnoreCase(ip))) {
              ip = request.getRemoteAddr();
            }
            return ip;
        }