Socket簡介

Socket又稱套接字，它是處于應用層和傳輸層之間的一個抽象接口。它封裝了TCP/UDP等的底層協議，通過它我們就可以實現應用程序或者進程之間（它們可以處在網絡上的不同位置）的通信。

Socket的表示方法

因為Socket是兩個程序之間的通信，只需要給定IP地址和端口號就可以進行通信。
Socket= （IP，PORT）

Socket（TCP）的工作流程

可以看到，總的工作流程就是：

1. 服務端監聽
2. 客戶端（可以有多個）請求連接
3. 確認連接進行通信

針對服務器端的工作流程是：

1. 建立Socket對象
2. Bind(ip, port)綁定端口。比如說本地的(127.0.0.1, 6666)
3. Listen()開始監聽
4. Accept(）接受客戶端連接
5. Send（）和Receive（）進行通信
6. Close()關閉套接字

而針對客戶端的工作流程是：

1. 建立Socket對象
2. Connet(ip, port)向某個IP下的PORT端口發起連接請求，接受后開始通信
3. Send()和Receive（）進行通信
4. Close() 關閉套接字

關于IPAddress.Parse("127.0.0.1") 和 Address.Any的問題，詳見；

https://blog.csdn.net/u010178308/article/details/77650919

代碼下載：https://github.com/urahyou/C-Sharp-Socket-example/tree/master

Server端代碼：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace socket
{
    class Program
    {

        static Socket serverSocket;
       
        

        static void Main(string[] args)
        {
            SetListen();  //開始監聽

        }

        static void SetListen()
        {
            serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            try
            {
                //這里最好改成IPAddress.Any, 這樣放到服務器上就會同時監聽所有網卡上的端口，比如有內外雙網的服務器
                serverSocket.Bind(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888));
                serverSocket.Listen(2);

                Thread thread = new Thread(Listen);
                thread.Start(serverSocket);

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            
        }

        static void Listen(object so)
        {
            Socket serverSocket = so as Socket;

            while (true)
            {
                try
                {
                    Socket clientSocket = serverSocket.Accept(); //接受客戶端接入
                    // 獲取鏈接IP地址
                    string clientPoint = clientSocket.RemoteEndPoint.ToString();

                    //開啟新線程來不停接受信息
                    Thread rec = new Thread(Receive);
                    rec.Start(clientSocket);

                    //開啟新線程來不停發送信息
                    Thread sen = new Thread(Send);
                    sen.Start(clientSocket);
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex.Message, ex);
                    break;
                }
            }
            serverSocket.Close();
        }

        static void Receive(object so)
        {
            Socket clientSocket = so as Socket;

            string clientPoint = clientSocket.RemoteEndPoint.ToString();
            while (true)
            {
                try
                {
                    byte[] buffer = new byte[1024];
                    int len = clientSocket.Receive(buffer);
                    //Console.WriteLine(len.ToString(), buffer);
                    if (len == 0) break;

                    string msg = Encoding.UTF8.GetString(buffer, 0, len);
                    Console.WriteLine("客戶端說："+ msg);
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex);
                }
            }
        }

        static void Send(object so)
        {
            Socket clientSocket = so as Socket;

            while (true)
            {
                //獲取控制臺輸入
                string input = Console.ReadLine();

                byte[] msg = Encoding.UTF8.GetBytes(input);
                clientSocket.Send(msg);
            }
        }
    }
}

Client端代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.Threading;



namespace socket_client
{
    class Program
    {
        static Socket clientSocket;

        static void Main(string[] args)
        {
            
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            
            //連接
            Connect(); 
        }

        //連接客戶端，連接后開始監聽發送過來的消息并且把輸入的信息發給服務端
        static void Connect()
        {
            clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 
            
            try
            {
                //連接
                clientSocket.Connect(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888));

                //獨立線程來接受來自服務端的數據
                Thread receive = new Thread(Receive);
                receive.Start(clientSocket);

                //獨立線程來發送數據給服務端
                Thread send = new Thread(Send);
                send.Start(clientSocket); 
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

        static void Receive(object so)
        {
            Socket clientSocket = so as Socket;


            while (true)
            {
                Console.ForegroundColor = ConsoleColor.Green;  // 修改文字顏色為綠色
                try
                {
                    byte[] buffer = new byte[1024];
                    int len = clientSocket.Receive(buffer);
                    if (len > 0)
                    {
                        string msg = Encoding.UTF8.GetString(buffer);
                        
                        Console.WriteLine("服務端說："+ msg);
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex);
                    break;
                }
            }
            clientSocket.Close();
        }

        static void Send(object so)
        {
            Socket clientSocket = so as Socket;

            while (true)  // 監聽鍵盤輸入
            {
                Console.ForegroundColor = ConsoleColor.Red;
                //獲取鍵盤輸入
                string input = Console.ReadLine();
                //編碼
                byte[] buffer = Encoding.UTF8.GetBytes(input);
                //發送
                clientSocket.Send(buffer);
            }
        }
    }
}