从Http请求中获取请求的实际IP地址

    public static String getRemoteIP(HttpServletRequest request) {
        String ip =null;
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            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();
        }
        if (ip != null) {
            //对于通过多个代理的情况，最后IP为客户端真实IP,多个IP按照','分割
            int position = ip.indexOf(",");
            if (position > 0) {
                ip = ip.substring(0, position);
            }
        }
        return ip;
    }