java获取HttpServletRequest 的客户端ip

public static String getIpAddress(HttpServletRequest request) {

        String ip = request.getHeader("X-Forwarded-For");

        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            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.getHeader("HTTP_CLIENT_IP");
            }
            if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
                ip = request.getHeader("HTTP_X_FORWARDED_FOR");
            }
            if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
                ip = request.getHeader("X-Real-IP");
            }
            if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
                ip = request.getRemoteAddr();
            }
        } else {
            String[] ips = ip.split(",");
            for (int index = 0; index < ips.length; index++) {
                String strIp = ips[index];
                if (!(UNKNOWN.equalsIgnoreCase(strIp))) {
                    ip = strIp;
                    break;
                }
            }
        }
        return ip;
    }