services.AddHttpClient();

class A
{
 private readonly IHttpClientFactory _clientFactory;
 public A(IHttpClientFactory clientFactory)
 {
  _clientFactory = clientFactory;
 }
 
 Public void Use()
 {
   var request=new HttpRequestMessage(HttpMethod.Get,"www.baidu.com") ;
   var client = _clientFactory.CreateClient();
   var response = await client.SendAsync(request); 
   if (response.IsSuccessStatusCode)
   {
   Branches = await response.Content.ReadAsAsync<IEnumerable<GitHubBranch>>();
   }
  else
  {
   GetBranchesError = true;
   Branches = Array.Empty<GitHubBranch>();
  }  
 }
}

services.AddHttpClient("baidu",c=>
{
 c.BaseAddress = new Uri("https://api.baidu.com/");
 //其他一些參數(shù)
});

 var client = _clientFactory.CreateClient("baidu");

services.AddHttpClient<classHttp>();

public class classHttp
{
   public HttpClient Client { get; }
   public GitHubService(HttpClient client)
   {
      client.BaseAddress = new Uri("https://api.baidu.com/");
      //同ConfigureServices 中一樣設(shè)置一些其他參數(shù)
      Client = client;
   }
}

public interface IHelloClient
{
  [Get("/MyInterFace")]
  Task<Reply> GetMessageAsync();
}

public void ConfigureServices(IServiceCollection services)
{
  services.AddHttpClient("hello", c =>
  {
    c.BaseAddress = new Uri("http://localhost:5000");
  })
  .AddTypedClient(c => Refit.RestService.For<IHelloClient>(c));

  services.AddMvc();
}

[ApiController]
public class TestController : ControllerBase
{
   [HttpGet("/")]
  public async Task<sting> MyInterFace()
  {
    return "ceshi";
  }
}

[ApiController]
public class ValuesController : ControllerBase
{
  private readonly IHelloClient _client;

  public ValuesController(IHelloClient client)
  {
    _client = client;
  }

  [HttpGet("/")]
  public async Task<ActionResult<Reply>> Index()
  {
    return await _client.GetMessageAsync();
  }
}

public class ValidateHeaderHandler : DelegatingHandler
{
  protected override async Task<HttpResponseMessage> SendAsync(
    HttpRequestMessage request,
    CancellationToken cancellationToken)
  {
    if (!request.Headers.Contains("X-API-KEY"))
    {
      return new HttpResponseMessage(HttpStatusCode.BadRequest)
      {
        Content = new StringContent(
          "You must supply an API key header called X-API-KEY")
      };
    }

    return await base.SendAsync(request, cancellationToken);
  }
}

services.AddTransient<ValidateHeaderHandler>();//注冊(cè)處理程序
services.AddHttpClient("externalservice", c =>
{
  // Assume this is an "external" service which requires an API KEY
  c.BaseAddress = new Uri("https://localhost:5000/");
})
.AddHttpMessageHandler<ValidateHeaderHandler>();/注入到http請(qǐng)求管道

services.AddHttpClient("extendedhandlerlifetime")
  .SetHandlerLifetime(TimeSpan.FromMinutes(5));