11 .NET Http请求-优快云博客

本文介绍了如何在.NET Core中使用Microsoft.Extensions.Http库，包括如何向IServiceCollection注册IHttpClientFactory，创建命名客户端，以及POST、PUT和DELETE请求示例。重点讲解了依赖注入和配置定制化HttpClient的行为。

包：Microsoft.Extensions.Http

向IServiceCollention注册IHttpClientFactory

Microsoft.Extensions.Http针对IServiceCollention提供了扩展方法AddHttpClient();

IHostBuilder builder = Host.CreateDefaultBuilder();
builder.ConfigureServices(services =>
{
    services.AddHttpClient();
});

基本使用

public class MyService
{
    private IHttpClientFactory _httpClientFactory { get; }

    // 依赖注入IHttpClientFactory
    public MyService(IHttpClientFactory httpClientFactory) {
        this._httpClientFactory = httpClientFactory;
    }

    public async Task Fetch(CancellationToken cancellationToken)
    {
        var request = new HttpRequestMessage(HttpMethod.Get, "https://api.github.com/repos/aspnet/docs/branches");
        request.Headers.Add("Accept", "application/vnd.github.v3+json");
        request.Headers.Add("User-Agent", "HttpClientFactory-Sample");

        // 生成 Http 客户端
        var client = _httpClientFactory.CreateClient();
        // 发送请求
        var response = await client.SendAsync(request);

        if (response.IsSuccessStatusCode)
        {
            string body = await response.Content.ReadAsStringAsync();
            Console.WriteLine("请求成功", body);
        }
        else
        {
            Console.WriteLine("请求失败");
        }
    }
}

命名客户端

我们可以注册命名的HttpClient

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

在创建时使用名称创建

// 创建命名客户端
var client = _clientFactory.CreateClient("github");

POST请求示例

public async Task CreateItemAsync(Item item)
{
    using StringContent json = new(
        JsonSerializer.Serialize(item, DefaultJsonSerialization.Options),
        Encoding.UTF8,
        MediaTypeNames.Application.Json);

using HttpResponseMessage httpResponse = await _httpClient.PostAsync("/api/items", json);

    httpResponse.EnsureSuccessStatusCode();
}

PUT请求示例

public async Task UpdateItemAsync(Item item)
{
    using StringContent json = new(
        JsonSerializer.Serialize(item, DefaultJsonSerialization.Options),
        Encoding.UTF8,
        MediaTypeNames.Application.Json);

using HttpResponseMessage httpResponse = await _httpClient.PutAsync($"/api/items/{item.Id}", json);

    httpResponse.EnsureSuccessStatusCode();
}

DELETE请求示例

public async Task DeleteItemAsync(Guid id)
{
    using HttpResponseMessage httpResponse =
        await _httpClient.DeleteAsync($"/api/items/{id}");

    httpResponse.EnsureSuccessStatusCode();
}