C# Network (Socket and NetworkStream)

The difference between Socket and NetworkStream:

In C#, Socket and NetworkStream are two different APIs for network communication. Socket provides a lower-level and flexible network communication function, which is suitable for scenarios with higher requirements for network transmission details. NetworkStream, on the other hand, is an advanced package based on Socket, which provides a simplified interface for reading and writing, and is suitable for most common network communication tasks.

Socket

tcp server

using System;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace ServerTcp
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建Socket
            Socket ServerTcp = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //绑定IP和端口
            IPAddress iPAddress = new IPAddress(new byte[] { 127,0,0,1 });
            EndPoint endPoint = new IPEndPoint(iPAddress, 7777);
            ServerTcp.Bind(endPoint);
            //监听，等待客户端进行链接
            Console.WriteLine("开始监听");
            ServerTcp.Listen(100);//开始监听，100为最大连接数
            Console.WriteLine("等待客户端链接");
            Socket client = ServerTcp.Accept();//接收客户端；实际上是暂停当前线程

            //向客户端发送消息
            string mess1 = "服务器正在运行";
            byte[] buffer = Encoding.UTF8.GetBytes(mess1);//字符串转为字节
            client.Send(buffer);
            while(true)
            {
                //接收客户端的消息
                byte[] data = new byte[1024];//定义缓存区
                int length = client.Receive(data);//信息的有效长度
                string mess2 = Encoding.UTF8.GetString(data, 0, length);
                Console.WriteLine("向客户端发送的消息：" + mess2);
            }
        }
    }
}

tcp client

using System;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace ClientTcp
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建Socket
            Socket tcpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //请求与服务器连接
            IPAddress ip = IPAddress.Parse("127.0.0.1");
            EndPoint endPoint = new IPEndPoint(ip,7777);
            tcpClient.Connect(endPoint);

            //接收消息
            byte[] buffer = new byte[1024];//定义缓存区
            int length = tcpClient.Receive(buffer);//将接收的数组放入缓存区，并返回字节数
            string message = Encoding.UTF8.GetString(buffer, 0, length);//对缓存区中的数据进行解码成字符串
            Console.WriteLine("从服务端接收的信息："+message);
            while(true)
            {
                //发送消息
                string str = Console.ReadLine();//输入发送的信息
                tcpClient.Send(Encoding.UTF8.GetBytes(str));//将string转成字节流后，发送消息
            }
        }
    }
}

udp server

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace UdpServer
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建Socket
            Socket udpServer = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            //绑定ip和端口
            EndPoint endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7777);
            udpServer.Bind(endPoint);

            while (true)
            {
                //接收消息
                EndPoint endPointSend = new IPEndPoint(IPAddress.Any, 0);//任意IP地址，任意端口
                byte[] data = new byte[1024];
                int length = udpServer.ReceiveFrom(data, ref endPointSend);
                string message = Encoding.UTF8.GetString(data, 0, length);
                Console.WriteLine("接收客户端发送的信息：" + message);
            }
        }
    }
}

udp client

using System;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace UdpClient
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建socket
            Socket udpClient = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            EndPoint endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7777);

            while (true)
            {
                //发送消息
                string message = Console.ReadLine();
                udpClient.SendTo(Encoding.UTF8.GetBytes(message), endPoint);
            }
        }
    }
}

NetworkStream

client

using System;
using System.Net.Sockets;
using System.Text;

namespace Client
{
    class Program
    {
        static void Main(string[] args)
        {
            //服务器IP和端口
            string serverIP = "127.0.0.1";
            int serverPort = 7777;
            //创建TCP客户端
            TcpClient client = new TcpClient();
            client.Connect(serverIP, serverPort);
            //获取网络流
            NetworkStream stream = client.GetStream();
            //发送消息给服务器
            string message = "这里是客户端！！";
            byte[] data = Encoding.UTF8.GetBytes(message);
            stream.Write(data, 0, data.Length);
            Console.WriteLine("客户端发送消息：" + message);
            // 读取服务器的响应
            byte[] buffer = new byte[1024];
            int bytesRead = stream.Read(buffer, 0, buffer.Length);
            string response = Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine("客户端接收到信息：" + response);
            // 关闭连接
            stream.Close();
            client.Close();
            Console.WriteLine("客户端连接已关闭");
            Console.ReadKey();
        }
    }
}

Server

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace Server
{
    class Program
    {
        static void Main(string[] args)
        {
            //定义ip和端口后开始监听
            IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
            int port = 7777;
            TcpListener listener = new TcpListener(ipAddress, port);
            listener.Start();
            Console.WriteLine("服务器正在运行，等待客户端连接");
            //接收客户端
            TcpClient client = listener.AcceptTcpClient();
            Console.WriteLine("客户端已经连接");
            //获取网络流
            NetworkStream steam = client.GetStream();
            //读取客户端发送的消息
            byte[] buffer = new byte[1024];
            int bytesRead = steam.Read(buffer, 0, buffer.Length);
            string message = Encoding.UTF8.GetString(buffer,0,bytesRead);
            Console.WriteLine("服务器接收到消息：" + message);
            //发送响应给客户端
            string response = "这里是服务器！！";
            byte[] data = Encoding.UTF8.GetBytes(response);
            steam.Write(data,0,data.Length);
            Console.WriteLine("服务器发送信息：" + response);
            //关闭连接
            steam.Close();
            client.Close();
            listener.Stop();
            Console.WriteLine("服务器连接关闭");
            Console.ReadKey();
        }
    }
}

reference:

Socket 类 (System.Net.Sockets) | Microsoft Learn