class EtherNet

    {

        public void Send(string data)

        {

            Console.WriteLine("EtherNet is Sending: {0}", data);

        }

    }

    class COM

    {

        public void Transform(string data)

        {

            Console.WriteLine("COM is Transforming :{0}", data);

        }

    }

    class USB

    {

        public void Transform(string data)

        {

            Console.WriteLine("USB is Transforming :{0}", data);

        }

}

//门面，把各种设备封装，对外提供统一的接口

    class IO

    {

         private EtherNet net;

         private COM com;

         private USB usb;

        public void Send(string data, string port)

        {

            switch (port)

            {

                case "net":

                    net = new EtherNet();

                    net.Send(data);

                    break;

                case "com":

                    com = new COM();

                    com.Transform(data);

                    break;

                case "usb":

                     usb = new USB();

                    usb.Transform(data);

                    break;

                default:

                    Console.WriteLine(" 对不起，没有此种设备！");

                    break;

            }

        }

    }

    class Computer

    {

        static private IO io;

        [STAThread]

        static void Main(string[] args)

        {

            Console.WriteLine(" 请指定设备端口：");

            string port = Console.ReadLine().ToLower();

            Console.WriteLine(" 请输入要发送的数据：");

            string data = Console.ReadLine().ToLower();

            io = new IO();

            io.Send(data, port);

        }

    }