C TCP client form application asynchronous receiving mode

1. Program interface design

Probably design a simple interface as follows .

2. Core code of each part

2.1 Connect server

When the request connection button is pressed , Will trigger a click event , Then make the connection server request .

private void btnConnect_Click(object sender, EventArgs e)
{
    
    try
    {
    
        if (IsConnected == false)
        {
    
            tcpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);    //  Create a Socket Socket  
            IPAddress ipaddress = IPAddress.Parse(cbbHostIP.Text);
            EndPoint point = new IPEndPoint(ipaddress, int.Parse(tbHostPort.Text));

            tcpClient.Connect(point);

            tcpClient.BeginReceive(recieveBuffer, 0, recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
            IsConnected = true;
            btnConnect.Text = " disconnect ";
        }
        else
        {
    
            tcpClient.Disconnect(false);
            IsConnected = false;
            btnConnect.Text = " Request connection ";
        }
    }
    catch (Exception ex)
    {
    
        MessageBox.Show(ex.ToString());
    }
}

When pressing connect , So let's create one socket Socket , Then get the server of user input from the control IP And port , Then connect .

most important of all , Here is the asynchronous receiving design , Set the receive callback function ReceiveCallback.

2.2 send data

Because sending data , It is the user who actively presses “ send out ” Button sent , So it's simpler , As long as there is a click event of pressing the send button , Just send the data .

private void btnSend_Click(object sender, EventArgs e)
{
    
    if (IsConnected == true)
    {
    
        tcpClient.Send(tbSend.Text.GetBytes("GBK"));
    }
    else
    {
    
        MessageBox.Show(" Please connect the server first ");
    }
}

2.3 receive data

The received data is received asynchronously , Because it is impossible to determine when the server will send data to the client .

private void ReceiveCallback(IAsyncResult AR)
{
    
    // Check how much bytes are recieved and call EndRecieve to finalize handshake
    try
    {
    
        int recieved = tcpClient.EndReceive(AR);

        if (recieved <= 0)
            return;

        string message = Encoding.GetEncoding("GBK").GetString(recieveBuffer, 0, recieved);     //  Only convert the received data 

        Print(message);

        // Start receiving again
        tcpClient.BeginReceive(recieveBuffer, 0, recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
    }
    catch (SocketException ex)
    {
    
        MessageBox.Show(ex.ToString());
    }
}

among ,ReceiveCallback Function is the callback function received . If there is data reception , Then the process of actually receiving data , It is completed in this callback function .

3. The source code of the whole project

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Windows.Forms;

namespace Net_assistance
{
    
    public partial class Form1 : Form
    {
    
        public static Socket tcpClient;
        bool IsConnected = false;
        private byte[] recieveBuffer = new byte[8142];

        public Form1()
        {
    
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
    
            //  Get locally available IP Address 
            string strHostIP = Dns.GetHostName();
            IPAddress[] ipadrlist = Dns.GetHostAddresses(strHostIP);
            foreach (IPAddress ipaddr in ipadrlist)
            {
    
                if (ipaddr.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
                    cbbHostIP.Items.Add(ipaddr.ToString());
            }
            cbbHostIP.Items.Add("127.0.0.1");   //  Finally, add the loopback test address 
            cbbHostIP.SelectedIndex = 0;

            tbHostPort.Text = "8080";

            tbSend.Text = "hello world!";
        }

        private void Print(string msg)
        {
    
            tbRecv.AppendText($"[{
      DateTime.Now.ToString("yyy-MM-dd HH.mm.ss.fff")}] {
      msg}\r\n");
        }


        private void ReceiveCallback(IAsyncResult AR)
        {
    
            // Check how much bytes are recieved and call EndRecieve to finalize handshake
            try
            {
    
                int recieved = tcpClient.EndReceive(AR);

                if (recieved <= 0)
                    return;

                string message = Encoding.GetEncoding("GBK").GetString(recieveBuffer, 0, recieved);     //  Only convert the received data 

                Print(message);

                // Start receiving again
                tcpClient.BeginReceive(recieveBuffer, 0, recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
            }
            catch (SocketException ex)
            {
    
                MessageBox.Show(ex.ToString());
            }
        }

        private void btnConnect_Click(object sender, EventArgs e)
        {
    
            try
            {
    
                if (IsConnected == false)
                {
    
                    tcpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);    //  Create a Socket Socket  
                    IPAddress ipaddress = IPAddress.Parse(cbbHostIP.Text);
                    EndPoint point = new IPEndPoint(ipaddress, int.Parse(tbHostPort.Text));

                    tcpClient.Connect(point);

                    tcpClient.BeginReceive(recieveBuffer, 0, recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
                    IsConnected = true;
                    btnConnect.Text = " disconnect ";
                }
                else
                {
    
                    tcpClient.Disconnect(false);
                    IsConnected = false;
                    btnConnect.Text = " Request connection ";
                }
            }
            catch (Exception ex)
            {
    
                MessageBox.Show(ex.ToString());
            }
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
    
            if (IsConnected == true)
            {
    
                tcpClient.Send(tbSend.Text.GetBytes("GBK"));
            }
            else
            {
    
                MessageBox.Show(" Please connect the server first ");
            }
        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
    
            if (IsConnected == true)
            {
    //  When you close a window , If you are connecting to the server , Then disconnect and exit 
                tcpClient.Disconnect(false);
            }
        }
    }
}

4. test

First open a server with the network debugging assistant . as follows ：

Then open the client program written by ourselves , Enter the... Of the server IP And port after , Click to connect . At this time, you can see that the server detects the access of the client , Then we can send and receive data from each other , The effect is as follows ：