獲取客戶端真實IP

網上常見的方式是：

 public static String getIpAddr(HttpServletRequest request) {
        String ip = request.getHeader("X-Forwarded-For");
        if (ip == null || "".equals(ip) || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || "".equals(ip) || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || "".equals(ip) || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        if (ip != null && !"".equals(ip)) {
            String[] ips = ip.split(",");
            for (int i = 0; i < ips.length; i++) {
                if (ips[i] != null && !"".equals(ips[i])
                        && !"unknown".equalsIgnoreCase(ips[i])) {
                    ip = ips[i];
                    break;
                }

            }
        }
        return ip;
    }

但是這種方式容易被篡改IP，所以一般是用 request.getHeader("X-Real-IP")
可以防止IP篡改繞過