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프로그램 설명

바이트 배열을 이용한 파일 전송을 구현한 예시입니다.

이미지 파일 전송시 데이타 구조와 일반 텍스트 데이타 구조가 다르므로 아래에 그림으로 표시했습니다.

실행 후

이미지 파일 전송 후

메시지 전송 후

프로그램 작성

1. 데이타 버퍼 클래스 (StateObject.cs)

    class StateObject
    {
        // Client socket
        public Socket workSocket = null;

        public const int BufferSize = 4096;

        // Receive buffer
        public byte[] buffer = new byte[BufferSize];
    }

2. 서버 프로그램

    public partial class MainForm : Form
    {
        bool initialFlag = true;
        string receivedPath = string.Empty;
        enum DataPacketType { TEXT = 1, IMAGE };
        int dataType = 0;
        string textData = string.Empty;

        public MainForm()
        {
            InitializeComponent();

            Thread t_handler = new Thread(StartListening);
            t_handler.IsBackground = true;
            t_handler.Start();
        }

        public static ManualResetEvent allDone = new ManualResetEvent(false);
        private void StartListening()
        {
            IPEndPoint localEP = new IPEndPoint(IPAddress.Any, 9050);
            Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            try
            {
                listener.Bind(localEP);
                listener.Listen(10);

                while(true)
                {
                    allDone.Reset();
                    listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
                    allDone.WaitOne();
                }
            }
            catch(SocketException se)
            {
                Trace.WriteLine(string.Format("SocketException :{0}", se.Message));
            }
            catch(Exception ex)
            {
                Trace.WriteLine(string.Format("Exception :{0}", ex.Message));
            }
        }

        private void AcceptCallback(IAsyncResult ar)
        {
            allDone.Set();

            Socket listener = ar.AsyncState as Socket;
            Socket handler = listener.EndAccept(ar);

            StateObject state = new StateObject();
            state.workSocket = handler;
            handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
            initialFlag = true;
        }

        private void ReadCallback(IAsyncResult ar)
        {
            int fileNameLen = 0;
            string content = string.Empty;
            StateObject state = ar.AsyncState as StateObject;
            Socket handler = state.workSocket;
            int bytesRead = handler.EndReceive(ar);
            
            if(bytesRead > 0)
            {                
                if (initialFlag)
                {
                    dataType = BitConverter.ToInt32(state.buffer, 0);
                    if (dataType == (int)DataPacketType.IMAGE)
                    { 
                        fileNameLen = BitConverter.ToInt32(state.buffer, 4);
                        string fileName = Encoding.UTF8.GetString(state.buffer, 8, fileNameLen);

                        string pathUser = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
                        string pathDownload = Path.Combine(pathUser, "Downloads");

                        receivedPath = Path.Combine(pathDownload, fileName);

                        if (File.Exists(receivedPath))
                            File.Delete(receivedPath);
                    }
                    else if (dataType == (int)DataPacketType.TEXT)
                    {
                        textData = Encoding.UTF8.GetString(state.buffer, 4, bytesRead - 4);
                        handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
                    }
                }

                if (dataType == (int)DataPacketType.IMAGE)
                {
                    BinaryWriter bw = new BinaryWriter(File.Open(receivedPath, FileMode.Append));
                    if (initialFlag)
                        bw.Write(state.buffer, 8 + fileNameLen, bytesRead - (8 + fileNameLen));
                    else
                        bw.Write(state.buffer, 0, bytesRead);

                    initialFlag = false;
                    bw.Close();
                    handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
                }
            }
            else
            {
                if (dataType == (int)DataPacketType.IMAGE)
                {
                    pictureBox1.ImageLocation = receivedPath;
                    Invoke((MethodInvoker)delegate
                    {
                        lblMessage.Text = "Data has been received";
                    });
                }
                else if (dataType == (int)DataPacketType.TEXT)
                    Invoke((MethodInvoker)delegate
                    {
                        textBox1.AppendText(textData + Environment.NewLine);
                    });
            }
        }
    }

3. 클라이언트 프로그램

    public partial class MainForm : Form
    {
        string m_splitter = "'\\'";
        string m_fName = string.Empty;
        string[] m_split = null;
        byte[] m_clientData = null;
        enum DataPacketType { TEXT = 1, IMAGE };

        public MainForm()
        {
            InitializeComponent();
            
        }

        private void btnBrowse_Click(object sender, EventArgs e)
        {
            char[] delimeter = m_splitter.ToCharArray();

            openFileDialog1.Filter = "Image files (*.jpg, *.jpeg, *.jpe, *.jfif, *.png) | *.jpg; *.jpeg; *.jpe; *.jfif; *.png";
            openFileDialog1.ShowDialog();

            textBox1.Text = openFileDialog1.FileName;
            pictureBox1.ImageLocation = openFileDialog1.FileName;

            m_split = textBox1.Text.Split(delimeter);
            int limit = m_split.Length;

            m_fName = m_split[limit - 1].ToString();

            if (textBox1.Text != null)
                btnSend.Enabled = true;
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            Thread t_handler = new Thread(SendData);
            t_handler.IsBackground = true;
            t_handler.Start();
        }

        private void SendData()
        {
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            byte[] fileName = Encoding.UTF8.GetBytes(m_fName);
            byte[] fileData = File.ReadAllBytes(textBox1.Text);
            byte[] fileNameLen = BitConverter.GetBytes(fileName.Length);
            byte[] fileType = BitConverter.GetBytes((int)DataPacketType.IMAGE);
            // IMAGE(4 byte) + 파일이름(4 byte) + 파일이름길이(4 byte) + 데이타 길이
            m_clientData = new byte[fileType.Length + 4 + fileName.Length + fileData.Length];

            fileType.CopyTo(m_clientData, 0);
            fileNameLen.CopyTo(m_clientData, 4);
            fileName.CopyTo(m_clientData, 8);
            fileData.CopyTo(m_clientData, 8 + fileName.Length);
            
            clientSocket.Connect(IPAddress.Parse("192.168.0.11"), 9050);
            clientSocket.Send(m_clientData);
            clientSocket.Close();
        }

        private void btnSendText_Click(object sender, EventArgs e)
        {
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            byte[] textData = Encoding.UTF8.GetBytes(textBox2.Text);
            byte[] fileType = BitConverter.GetBytes((int)DataPacketType.TEXT);
            // TEXT(4 byte) + 데이타 길이
            m_clientData = new byte[fileType.Length + textData.Length];

            fileType.CopyTo(m_clientData, 0);
            textData.CopyTo(m_clientData, 4);

            clientSocket.Connect(IPAddress.Parse("192.168.0.11"), 9050);
            clientSocket.Send(m_clientData);
            clientSocket.Close();
        }
    }