public void sendUdp()
        {
            string str = "I'm running";

            UdpClient udp = new UdpClient(2525);
            try
            {
                while (true)
                {
                    IPAddress ipAdd = IPAddress.Parse("255.255.255.255");
                    IPEndPoint end = new IPEndPoint(ipAdd, 2020);
                    
                    try
                    {
                        byte[] sendByte = Encoding.Unicode.GetBytes(str);
                        udp.Send(sendByte, sendByte.Length, end);
                    }
                    catch (Exception)
                    {
                        throw;
                    }
                        Thread.Sleep(3000);
                }
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message);
                throw;
            }
        }

        public void sendTcp(string ipAddress,string str) 
        {
            IPAddress ip = IPAddress.Parse(ipAddress);
            IPEndPoint ipep = new IPEndPoint(ip, 2025);

            //创建套接字   
            Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //连接到发送端 
            try
            {
                    client.Connect(ipep);
            }
            catch (Exception) 
            {
                MessageBox.Show("指定的从服务器已意外关闭， 链接不上");
            }
            if (client.Connected)
            {
                try
                {
                    this.SendVarData(client, Encoding.Unicode.GetBytes(str));
                }
                catch (Exception)
                {
                    MessageBox.Show("传输文件失败！");
                    throw;
                }

        public static int SendVarData(Socket s, byte[] data)
        {
            int total = 0;
            int size = data.Length;
            int dataleft = size;
            int sent;
            byte[] datasize = new byte[4];
            datasize = BitConverter.GetBytes(size);
            sent = s.Send(datasize);

            while (total < size)
            {
                sent = s.Send(data, total, dataleft, SocketFlags.None);
                total += sent;
                dataleft -= sent;
            }

            return total;
        }