java如何获取发起请求的用户真实IP

/**
     * 获取用户实际IP地址
     * @param request 当前请求对象
     * @return 实际IP地址
     */
    public static String getRemoteIp(HttpServletRequest request) {
        String ip = request.getHeader("X-Forwarded-For");
        logger.trace("当前IP来源[X-Forwarded-For], 值[{}]", ip);
        if(!StringUtils.isEmpty(ip) && !NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)){
            //多次反向代理后会有多个ip值，第一个ip才是真实ip
            int index = ip.indexOf(',');
            if(index != -1){
                return ip.substring(0, index);
            }else{
                return ip;
            }
        }
        ip = request.getHeader("X-Real-IP");
        logger.trace("当前IP来源[X-Real-IP], 值[{}]", ip);
        if(!StringUtils.isEmpty(ip) && !NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)){
            return ip;
        }
        if (StringUtils.isEmpty(ip) || NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
            logger.trace("当前IP来源[Proxy-Client-IP], 值[{}]", ip);
        }
        if (StringUtils.isEmpty(ip) || NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
            logger.trace("当前IP来源[WL-Proxy-Client-IP], 值[{}]", ip);
        }
        if (StringUtils.isEmpty(ip) || NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_CLIENT_IP");
            logger.trace("当前IP来源[HTTP_CLIENT_IP], 值[{}]", ip);
        }
        if (StringUtils.isEmpty(ip) || NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
            logger.trace("当前IP来源[HTTP_X_FORWARDED_FOR], 值[{}]", ip);
        }
        if (StringUtils.isEmpty(ip) || NoticeConstant.UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
            logger.trace("当前IP来源[getRemoteAddr], 值[{}]", ip);
        }
        if ("0:0:0:0:0:0:0:1".equals(ip)) {
            String ipv4FromLocal = getIpv4FromLocal();
            if (StringUtils.isNotEmpty(ipv4FromLocal)) {
                ip = ipv4FromLocal;
            }
        }
        return ip;
    }

    /**
     * 获取本地IP地址
     * @return IP地址
     */
    private static String getIpv4FromLocal() {
        String ip = null;
        InputStream is = null;
        InputStreamReader isr = null;
        BufferedReader br = null;
        try {
            Process process = Runtime.getRuntime().exec("cmd.exe /c ipconfig | findstr IPv4");
            is = process.getInputStream();
            isr = new InputStreamReader(is);
            br = new BufferedReader(isr);
            String line = br.readLine();
            ip = line.substring(line.indexOf(':') + 1).trim();
        } catch (IOException e) {
            logger.warn("获取本地IP异常", e);
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
                if (isr != null) {
                    isr.close();
                }
                if (is != null) {
                    is.close();
                }
            } catch (IOException e) {
                logger.debug("流关闭异常", e);
            }
        }
        return ip;
    }

    protected static String getRemoteAddr(HttpServletRequest request) {
        String caller = request.getHeader("X-Forwarded-For");
        if (caller == null || caller.isEmpty() || caller.equals("unknown")) {
            caller = request.getHeader("Proxy-Client-IP");
        }

        if (caller == null || caller.isEmpty() || caller.equals("unknown")) {
            caller = request.getHeader("WL-Proxy-Client-IP");
        }
        
        if (caller == null || caller.isEmpty() || caller.equals("un")) {
            caller = request.getHeader("HTTP_CLIENT_IP");
        }

        if (caller == null || caller.isEmpty() || caller.equals("un")) {
            caller = request.getHeader("X-Real-IP");
        }

        if (caller == null || caller.isEmpty() || caller.equals("unknown")) {
            caller = request.getRemoteAddr();
        }
        return caller;
    }