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白骑士的C#教学高级篇 3.3 网络编程

news 2025/7/9 10:23:48

网络编程是现代应用程序开发中至关重要的一部分。C# 提供了一套丰富的 API 来处理基本网络通信、Web请求与响应。在本节中，我们将深入探讨这些内容，帮助您掌握如何在 C# 中进行网络编程。

基本网络通信

基本网络通信通常涉及套接字（Socket）编程。C# 提供了 ‘System.Net.Sockets‘ 命名空间来处理套接字编程，使得开发者可以创建客户端和服务器应用程序。

以下是使用 TCP 套接字创建一个简单的客户端-服务器应用程序的方法示例：

服务器端

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;public class Server
{public static void Main(){TcpListener server = null;try{int port = 13000;IPAddress localAddr = IPAddress.Parse("127.0.0.1");server = new TcpListener(localAddr, port);server.Start();byte[] bytes = new byte[256];string data = null;while (true){Console.Write("Waiting for a connection... ");TcpClient client = server.AcceptTcpClient();Console.WriteLine("Connected!");data = null;NetworkStream stream = client.GetStream();int i;while ((i = stream.Read(bytes, 0, bytes.Length)) != 0){data = Encoding.ASCII.GetString(bytes, 0, i);Console.WriteLine($"Received: {data}");data = data.ToUpper();byte[] msg = Encoding.ASCII.GetBytes(data);stream.Write(msg, 0, msg.Length);Console.WriteLine($"Sent: {data}");}client.Close();}}catch (SocketException e){Console.WriteLine($"SocketException: {e}");}finally{server.Stop();}Console.WriteLine("\nHit enter to continue...");Console.Read();}
}

客户端

using System;
using System.Net.Sockets;
using System.Text;public class Client
{public static void Main(){try{Int32 port = 13000;TcpClient client = new TcpClient("127.0.0.1", port);NetworkStream stream = client.GetStream();string message = "Hello, Server!";byte[] data = Encoding.ASCII.GetBytes(message);stream.Write(data, 0, data.Length);Console.WriteLine($"Sent: {message}");data = new byte[256];string responseData = string.Empty;Int32 bytes = stream.Read(data, 0, data.Length);responseData = Encoding.ASCII.GetString(data, 0, bytes);Console.WriteLine($"Received: {responseData}");stream.Close();client.Close();}catch (ArgumentNullException e){Console.WriteLine($"ArgumentNullException: {e}");}catch (SocketException e){Console.WriteLine($"SocketException: {e}");}Console.WriteLine("\nHit enter to continue...");Console.Read();}
}

在这个示例中，服务器端使用 ‘TcpListener‘ 类监听连接请求，客户端使用 ‘TcpClient‘ 类连接到服务器并发送数据。

Web请求与响应

Web请求与响应是网络编程中的常见操作。C# 提供了 ‘System.Net.Http‘ 命名空间，用于处理 HTTP 请求和响应。

发送 GET 请求

using System;
using System.Net.Http;
using System.Threading.Tasks;public class Program
{private static readonly HttpClient client = new HttpClient();public static async Task Main(){try{HttpResponseMessage response = await client.GetAsync("https://api.github.com/repos/dotnet/docs/issues");response.EnsureSuccessStatusCode();string responseBody = await response.Content.ReadAsStringAsync();Console.WriteLine(responseBody);}catch (HttpRequestException e){Console.WriteLine($"Request exception: {e.Message}");}}
}

在这个示例中，使用 ‘HttpClient‘ 类发送 GET 请求，并读取响应内容。

发送 POST 请求

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;public class Program
{private static readonly HttpClient client = new HttpClient();public static async Task Main(){var values = new Dictionary<string, string>{{ "username", "example" },{ "password", "password" }};var content = new FormUrlEncodedContent(values);try{HttpResponseMessage response = await client.PostAsync("https://example.com/api/login", content);response.EnsureSuccessStatusCode();string responseBody = await response.Content.ReadAsStringAsync();Console.WriteLine(responseBody);}catch (HttpRequestException e){Console.WriteLine($"Request exception: {e.Message}");}}
}

在这个示例中，使用 ‘HttpClient‘ 类发送 POST 请求，并读取响应内容。