Question

我需要使用HttpClientFactory连接到外部api。 Startup.cs中的代码看起来像这样

public void SetUpHttpClients(IServiceCollection services)
{
        var loginEndpoint = Path.Combine(baseApi, "api/authentication);
        var fileExists = File.Exists(certificatePath);

        if (!fileExists)
            throw new ArgumentException(certificatePath);

        var certificate = new X509Certificate2(certificatePath, certPwd);

        services.AddHttpClient("TestClient", client =>
        {
        client.BaseAddress = new Uri(baseApi);
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(accept));
        client.DefaultRequestHeaders.Add("ApiKey", apiKey);

        var body = new { Username = username, Password = password };
        var jsonBody = JsonConvert.SerializeObject(body);
        var content = new StringContent(jsonBody, Encoding.UTF8, contentType);

        var loginResponse = client.PostAsync(loginEndpoint, content).Result;

        }).ConfigurePrimaryHttpMessageHandler(() =>
        {
            var cookieContainer = new CookieContainer();
            var handler = new HttpClientHandler
            {
                CookieContainer = cookieContainer
            };
            handler.ClientCertificates.Add(certificate);
            return handler;
});

我已使用HttpClientFactory将此代码添加到MessageController中，

public class MessagesController : Controller
{
    private readonly IHttpClientFactory _httpClientFactory;

    public ValuesController(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

   [HttpGet]
    public IActionResult GetMessages()
    {
        var client = _httpClientFactory.CreateClient("TestClient");
        var result = client.GetStringAsync("/api/messages");
        return Ok(result);
    }
}

但是当我尝试连接并从HttpClientFactory获取消息时，出现此错误：

无法加载资源：net :: ERR_CONNECTION_RESET，404-BadRequest

Answer 1

您试图在完成出厂配置之前发出请求，因为您在尝试配置客户端的同时仍在尝试使用该客户端，因此该帖子会失败。

这里的假设是在SetUpHttpClients中正在调用ConfigureServices。

public void ConfigureServices(IServiceCollection services) {
    //...

    SetUpHttpClients(services);

    //...

    services.AddMvc();
}

public void SetUpHttpClients(IServiceCollection services) {
    var basePath = Directory.GetCurrentDirectory();
    var certificatePath = Path.Combine(basePath, certPath);
    var fileExists = File.Exists(certificatePath);

    if (!fileExists)
        throw new ArgumentException(certificatePath);

    var certificate = new X509Certificate2(certificatePath, certPwd);

    //Adding a named client
    services.AddHttpClient("TestClient", client => {
        client.BaseAddress = new Uri(baseApi);
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(accept));
        client.DefaultRequestHeaders.Add("ApiKey", apiKey);
    })
    .ConfigurePrimaryHttpMessageHandler(() => {
        var cookieContainer = new CookieContainer();
        var handler = new HttpClientHandler {
            CookieContainer = cookieContainer
        };
        handler.ClientCertificates.Add(certificate);
        return handler;
    });
}

完成配置后，工厂可根据需要注入到控制器或服务类中。

以下示例显示了使用工厂作为控制器的依赖项。

[Route("api/[controller]")]
public class ValuesController : Controller {
    private readonly IHttpClientFactory factory;

    public MyController(IHttpClientFactory factory) {
        this.factory = factory;
    }

    [HttpGet]
    public async Task<IActionResult> Get() {
        var client = factory.CreateClient("TestClient");
        var result = client.GetStringAsync("api/messages");
        return Ok(result);
    }
}

在上面，工厂用于创建命名客户端的实例。它将具有在启动过程中设置的所有配置，其中包括带有证书的客户端处理程序。

要能够在启动过程中使用客户端（我建议不要这样做），首先需要将服务集合构建到服务提供程序中。

var serviceProvider = services.BuildServiceProvider();
var factory = serviceProvider.GetService<IHttpClientFactory>();
var client = factory.CreateClient("TestClient");

var body = new { Username = username, Password = password };
var jsonBody = JsonConvert.SerializeObject(body);
var content = new StringContent(jsonBody, Encoding.UTF8, contentType);

var loginResponse = client.PostAsync("api/authentication", content).Result;

//...do something with the response

但是，这可能会带来无法预料的结果，因为在启动过程的这一阶段，服务集合还没有完全填充。

Answer 2

我已经解决了这个问题。 SetUpHttpClient方法如下：

public void SetUpHttpClients(IServiceCollection services)
{
    var basePath = Directory.GetCurrentDirectory();
    var certificatePath = Path.Combine(basePath, CertPath);

    var fileExists = File.Exists(certificatePath);
    if (!fileExists)
        throw new ArgumentException(certificatePath);

    var certificate = new X509Certificate2(certificatePath, CertPwd);

    services.AddHttpClient("TestClient", client =>
    {
        client.BaseAddress = new Uri(BaseApi);
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(Accept));
        client.DefaultRequestHeaders.Add("ApiKey", ApiKey);

    }).ConfigurePrimaryHttpMessageHandler(() =>
    {
        var handler = new HttpClientHandler();
        handler.ClientCertificates.Add(certificate);
        return handler;
    });
}

我已添加到服务并从控制器调用的登录和消息的其余代码。

MessageClient.cs

    public MessageClient(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;

        _client = _httpClientFactory.CreateClient("TestClient");

        var body = new { UserName = Username, UserPassword = Password };
        var jsonBody = JsonConvert.SerializeObject(body);
        var content = new StringContent(jsonBody, Encoding.UTF8, ContentType);

        var loginEndpoint = Path.Combine(BaseApi, "api/authentication");

        _responseMessage = _client.PostAsync(loginEndpoint, content).Result;
    }

    public async Task<string> ReadMessages()
    {
        try
        {
            string messages = "";

            if (_responseMessage.IsSuccessStatusCode)
            {
                var messagesEndpoint = Path.Combine(BaseApi, "api/messages/");
                var cookieContainer = new CookieContainer();
                var handler = new HttpClientHandler { CookieContainer = cookieContainer };
                var cookiesToSet = GetCookiesToSet(_responseMessage.Headers, BaseApi);

                foreach (var cookie in cookiesToSet)
                {
                    handler.CookieContainer.Add(cookie);
                }
                var messageResponse = await _client.GetAsync(messagesEndpoint);
                messages = await messageResponse.Content.ReadAsStringAsync();
            }
            return messages;
        }
        catch (Exception e)
        {
            throw e.InnerException;
        }
    }

MessageContoller.cs

[HttpGet]
public async Task<ActionResult> GetMessages()
{
  var result = await _messageClient.ReadMessages();
  return Ok(result);
}

感谢@Nkosi。

HttpClientFactory BadRequest吗？

2 个答案: