我们如何在 ASP.Net Core 中使用 HttpClient？

Question

我正在编写 ASP.Net MVC Core 2.2 Web 应用程序。我需要使用 HTTP 或 HTTPS 从另一个 Web 服务器获取数据。我应该怎么做？

我使用 HttpClient.

编写代码

我有一个接收消息的控制器，它工作正常，但是，我应该构建 HttpClient 吗？

[Route("api/[controller]")]
[ApiController]
public class MyController : ControllerBase
{
    private readonly IHostingEnvironment _env;
    private readonly ILogger _logger;
    private readonly IUpdateService _updateService;

    public MyController(
        IHostingEnvironment env,
        ILogger<MyController> logger,
        IUpdateService updateService)
    {
        _env = env;
        _logger = logger;
        _updateService = updateService;
    }

    // POST api/values
    [HttpPost]
    public async Task<IAsyncResult> Post([FromBody]Update update)
    {
        using (HttpClient Client = new HttpClient())
        {
            HttpResponseMessage result = Client.GetAsync(uri).Result;
            switch (result.StatusCode)
            {
                case HttpStatusCode.Accepted:
                    return true;
                case HttpStatusCode.OK:
                    return true;
                default:
                    return false;
            }
        }
    }
}

Answer 1

Microsoft documentation here.

在ConfigureServices中注册HttpClient。

1a。 typed clients

services.AddHttpClient<ITypedClientService, TypedClientService>();

1b。 named clients

services.AddHttpClient("someClient", c =>
{
    c.BaseAddress = new Uri("https://someaddress.com/");
});

1c。 Basic usage

services.AddHttpClient();

将 HttpClient 注入您的控制器。

[ApiController]
public class BotController : ControllerBase
{
    ...

2a。 typed clients

    public BotController(..., ITypedClientService httpClient, ...)
    {
        ...
        _httpClient = httpClient;
        ...
    }

2b。 named clients

    public BotController(..., IHttpClientFactory clientFactory, ...)
    {
        ...
        _httpClient = clientFactory.createClient("someClient");
        ...
    }

2c。 Basic usage

    IHttpClientFactory _clientFactory

    public BotController(..., IHttpClientFactory clientFactory, ...)
    {
        ...
        _clientFactory = clientFactory; 
        ...
    }

    [HttpPost]
    public async Task<IActionResult> Post([FromBody]Update update)
    {
        ...
        var request = new HttpRequestMessage(
            HttpMethod.Get, 
            "https://someaddress.com/api/resource");
        request.Headers.Add("Accept", "application/vnd.github.v3+json");
        request.Headers.Add("User-Agent", "YourApp");
        var client = _clientFactory.createClient();
        var response = await client.SendAsync(request);
        ...
    }

不要自己构造HttpClient，新的就是胶水。让 HttpClientFactory 和框架管理生命周期和实例化。

注, 使用基本用法，您可以避免为定义的客户端配置策略的好处。

我们如何在 ASP.Net Core 中使用 HttpClient？

How can we use HttpClient in ASP.Net Core?

c#

asp.net-core

asp.net-core-2.0