DotNetCore.SKIT.FlurlHttpClient.Wechat/docs/WechatApi/Advanced_IHttpClientFactory.md

如何在 ASP.NET Core 中与 IHttpClientFactory 集成？

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请参阅：

《Microsoft Docs - 使用 IHttpClientFactory 实现复原 HTTP 请求》

《Microsoft Docs - 在 ASP.NET Core 中使用 IHttpClientFactory 发出 HTTP 请求》

《Microsoft Docs - .NET Core 2.1 的新增功能：套接字改进》

当你的项目是运行在 ASP.NET Core 2.1 或更高版本的平台时，CLR 已经提供了全新的底层套接字实现，无需你手动干预 HttpClient 的生命周期。

如果你想手动管理 HttpClient，那么可以参考下面基于 DI/IoC 的代码实现：

using Microsoft.Extensions.Options;
using SKIT.FlurlHttpClient.Wechat.Api;
using SKIT.FlurlHttpClient.Wechat.Api.Models;

public class WechatApiClientFactory
{
    internal class DelegatingFlurlClientFactory : Flurl.Http.Configuration.DefaultHttpClientFactory
    {
        private readonly System.Net.Http.IHttpClientFactory _httpClientFactory;

        public DelegatingFlurlClientFactory(System.Net.Http.IHttpClientFactory httpClientFactory)
        {
            _httpClientFactory = httpClientFactory ?? throw new ArgumentNullException(nameof(httpClientFactory));
        }

        public override System.Net.Http.HttpClient CreateHttpClient(System.Net.Http.HttpMessageHandler handler)
        {
            return _httpClientFactory.CreateClient();
        }
    }

    private readonly System.Net.Http.IHttpClientFactory _httpClientFactory;
    private readonly IOptions<WechatApiClientOptions> _wechatApiClientOptions;

    public WechatApiClientFactory(
        System.Net.Http.IHttpClientFactory httpClientFactory,
        IOptions<WechatApiClientOptions> wechatApiClientOptions)
    {
        _httpClientFactory = httpClientFactory ?? throw new ArgumentNullException(nameof(httpClientFactory));
        _wechatApiClientOptions = wechatApiClientOptions ?? throw new ArgumentNullException(nameof(wechatApiClientOptions));
    }

    public WechatApiClient CreateClient()
    {
        WechatApiClient client = new WechatApiClient(_wechatApiClientOptions.Value);
        client.Configure((settings) => settings.FlurlHttpClientFactory = new DelegatingFlurlClientFactory(_httpClientFactory));
        return client;
    }
}

需要强调的是，虽然 WechatApiClient 实现了 System.IDisposable 接口，但你不应该在 DI/IoC 中手动释放它，而是应该交给 IoC 容器自动管理它。

此外你应注意，System.Net.Http.IHttpClientFactory 与 Flurl.Http.Configuration.IHttpClientFactory 是两个不同的类型，使用时请加以区分。