java 获取IP地址的方法

今天有一个需求需要保存请求的IP地址，所有写了这么一个方法，记录下来以防以后要用到这个东西：

private 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();

        }

        return ip;

      }