.NetCore【工作应用】HttpClient

IHttpClientFactory

在项目中经常有遇到调用第三方接口的情况，一般我们使用HttpClient来请求调用第三方接口，.net core 中可以使用HttpClientFactory来管理HttpClient

直接使用IHttpClientFactory

先注册服务

public void ConfigureServices(IServiceCollection services)
{
    //HttpClient
    services.AddHttpClient();

}

之后在控制器中使用

public class ThirdRequestController : ControllerBase
{

    private readonly IHttpClientFactory _httpClientFactory;
    public ThirdRequestController(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    [HttpGet]
    public async Task<ActionResult> Get()
    {
        var client = _httpClientFactory.CreateClient();
        string result = await client.GetStringAsync("/");
        return Ok(result);
    }
}

通过HttpClient名字生成HttpClient

实际在工作使用中，我们经常需要对第三方的接口进行调用，而第三方的请求一般都会加上一下特定的请求头，例如token，不想在每个请求时都代码加上token，可以包装出一个Client出来

注册时可以添加有一个name的HttpClient

services.AddHttpClient();
services.AddHttpClient("github", c =>
{
    c.BaseAddress = new Uri("https://api.github.com/");
    c.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
    c.DefaultRequestHeaders.Add("User-Agent", "HttpClientFactory-Sample");
});

使用时，根据name获取对应的HttpClient

var client = _httpClientFactory.CreateClient("github");

使用自定义HttpClient生成

觉得这么多代码写在注册代码不方便，而且有很多第三方接口时，代码也很混乱，可以把每个HttpClient封装一下

public class GitHubClient
{
    public HttpClient Client { get; private set; }
    
    public GitHubClient(HttpClient httpClient)
    {
        httpClient.BaseAddress = new Uri("https://api.github.com/");
        httpClient.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
        httpClient.DefaultRequestHeaders.Add("User-Agent", "HttpClientFactory-Sample");
        Client = httpClient;
    }
}


// 注册时

services.AddHttpClient<GitHubClient>();


// 控制器中使用
public class ValuesController : Controller
{
    private readonly GitHubClient _gitHubClient;;

    public ValuesController(GitHubClient gitHubClient)
    {
        _gitHubClient = gitHubClient;
    }

    [HttpGet]
    public async Task<ActionResult> Get()
    {
        string result = await _gitHubClient.client.GetStringAsync("/");
        return Ok(result);
    }
}

将调用方法也放在自定义HttpClient中

调用第三方接口时可能不止一个请求接口，写在不同的地方很混乱，就想着把他们都放在这个GitHubClient中

public interface IGitHubClient
{
    Task<string> GetData();
}

public class GitHubClient : IGitHubClient
{
    private readonly HttpClient _client;

    public GitHubClient(HttpClient httpClient)
    {
        httpClient.BaseAddress = new Uri("https://api.github.com/");
        httpClient.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
        httpClient.DefaultRequestHeaders.Add("User-Agent", "HttpClientFactory-Sample");
        _client = httpClient;
    }

    public async Task<string> GetData()
    {
        return await _client.GetStringAsync("/");
    }
}


// 注册服务

services.AddHttpClient<IGitHubClient, GitHubClient>();


// 使用时
string result = await _gitHubClient.GetData();