多级反向代理java获取真实IP地址

public static String getIpAddress(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.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.getRemoteAddr();
        }
        System.out.println(ip);
        return ip;
      }

如果是多级反向代理上面方法不不行的话会出现 x-forwarded-for获取的地址是一长串的多个ip地址

public static String getIpAddress(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.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.getRemoteAddr();
            if(ip.equals("127.0.0.1") || ip.equals("0:0:0:0:0:0:0:1")){
                //根据网卡取本机配置的IP
                InetAddress inet=null;
                try {
                    inet = InetAddress.getLocalHost();
                } catch (UnknownHostException e) {
                    e.printStackTrace();
                }
                ip= inet.getHostAddress();
            }

        }
        //对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
        if(ip!=null && ip.length()>15) { //"***.***.***.***".length() = 15
            if (ip.indexOf(",") > 0) {
                ip = ip.substring(0, ip.indexOf(","));
            }
        }
        System.out.println(ip);
        return ip;
      }