java如何获取客户端登入时的ip

/**
 * 通过HttpServletRequest返回IP地址
 * @param request HttpServletRequest
 * @return ip String
 * @throws Exception
 */
public String getIpAddr(HttpServletRequest request) throws Exception {
    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;
}



 /**
 * 通过IP地址获取MAC地址
 * @param ip String,127.0.0.1格式
 * @return mac String
 * @throws Exception
 */
public String getMACAddress(String ip) throws Exception {
    String line = "";
    String macAddress = "";
    final String MAC_ADDRESS_PREFIX = "MAC Address = ";
    final String LOOPBACK_ADDRESS = "127.0.0.1";
    //如果为127.0.0.1,则获取本地MAC地址。
    if (LOOPBACK_ADDRESS.equals(ip)) {
        InetAddress inetAddress = InetAddress.getLocalHost();
        //貌似此方法需要JDK1.6。
        byte[] mac = NetworkInterface.getByInetAddress(inetAddress).getHardwareAddress();
        //下面代码是把mac地址拼装成String
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < mac.length; i++) {
            if (i != 0) {
                sb.append("-");
            }
            //mac[i] & 0xFF 是为了把byte转化为正整数
            String s = Integer.toHexString(mac[i] & 0xFF);
            sb.append(s.length() == 1 ? 0 + s : s);
        }
        //把字符串所有小写字母改为大写成为正规的mac地址并返回
        macAddress = sb.toString().trim().toUpperCase();
        return macAddress;
    }
    //获取非本地IP的MAC地址
    try {
        Process p = Runtime.getRuntime().exec("nbtstat -A " + ip);
        InputStreamReader isr = new InputStreamReader(p.getInputStream());
        BufferedReader br = new BufferedReader(isr);
        while ((line = br.readLine()) != null) {
            if (line != null) {
                int index = line.indexOf(MAC_ADDRESS_PREFIX);
                if (index != -1) {
                    macAddress = line.substring(index + MAC_ADDRESS_PREFIX.length()).trim().toUpperCase();
                }
            }
        }
        br.close();
    } catch (IOException e) {
        e.printStackTrace(System.out);
    }
    return macAddress;
}