在 ASP.NET Core 中使用 IHttpClientFactory 发出 HTTP 请求

using System;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
class Program
    static async Task<int> Main(string[] args)
        var builder = new HostBuilder()
            .ConfigureServices((hostContext, services) =>
                services.AddHttpClient();
                services.AddTransient<IMyService, MyService>();
            }).UseConsoleLifetime();
        var host = builder.Build();
            var myService = host.Services.GetRequiredService<IMyService>();
            var pageContent = await myService.GetPage();
            Console.WriteLine(pageContent.Substring(0, 500));
        catch (Exception ex)
            var logger = host.Services.GetRequiredService<ILogger<Program>>();
            logger.LogError(ex, "An error occurred.");
        return 0;
    public interface IMyService
        Task<string> GetPage();
    public class MyService : IMyService
        private readonly IHttpClientFactory _clientFactory;
        public MyService(IHttpClientFactory clientFactory)
            _clientFactory = clientFactory;
        public async Task<string> GetPage()
            // Content from BBC One: Dr. Who website (©BBC)
            var request = new HttpRequestMessage(HttpMethod.Get,
                "https://www.bbc.co.uk/programmes/b006q2x0");
            var client = _clientFactory.CreateClient();
            var response = await client.SendAsync(request);
            if (response.IsSuccessStatusCode)
                return await response.Content.ReadAsStringAsync();
                return $"StatusCode: {response.StatusCode}";
标头传播中间件
标头传播是一个 ASP.NET Core 中间件，可将 HTTP 标头从传入请求传播到传出 HTTP 客户端请求。 使用标头传播：
引用 Microsoft.AspNetCore.HeaderPropagation 包。
在 Startup 中配置中间件和 HttpClient：
C#