/**
     * 將域名轉換成IP，若返回null，則判斷失敗
     * @param host
     * @return
     */
    public String GetInetAddress(String host) {
        String IPAddress = "";
        InetAddress ReturnStr1 = null;
        try {
            ReturnStr1 = java.net.InetAddress.getByName(host);
            IPAddress = ReturnStr1.getHostAddress();
        } catch (UnknownHostException e) {
            e.printStackTrace();
            return IPAddress;
        }
        return IPAddress;
    }

    /**
     * 判斷IP版本是IPv4還是IPv6，若返回null，則判斷失敗
     * @param host
     * @return
     */
    public String GetIPVersion(String host) {
        InetAddress ReturnStr1 = null;
        try {
            ReturnStr1 = java.net.InetAddress.getByName(host);
            if (ReturnStr1.getAddress().length == 4) {
                return "ipv4";
            } else {
                return "ipv6";
            }
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
        return null;
    }