使用HttpClientFactory添加导致错误的cancellationTokenSource

Question

我对HttpClientFactory有一个问题，我试图将一个CancellationTokenSource从DI注入到配置为a的"SomeClient“中：

services.AddHttpClient<ISomeClient, SomeClient>(a =>
                a.BaseAddress = new Uri(address))

我在cancellationTokenSource ()中注入Startup.cs中的AddScoped<>。

如果我将CancellationTokenSource添加到SomeClient构造函数中，它会说

无法从根提供程序解析范围内的服务“System.Threading.CancellationTokenSource”。

但如果我创造出这样的东西：

services.AddScoped<ISomeClient, SomeClient>();

并在构造函数中创建一个新的本地HttpClient，并注入CancellationTokenSource，一切都会好起来的。

那么，我的问题是如何将CancellationTokenSource与HttpClientFactory结合使用？

Answer 1

对于AddHttpClient，它将SomeClient注册为Transient。但您将CancellationTokenSource注册为Scoped。这是根源造成的。

HttpClientFactoryServiceCollectionExtensions.cs

    public static IHttpClientBuilder AddHttpClient<TClient>(this IServiceCollection services)
        where TClient : class
    {
        if (services == null)
        {
            throw new ArgumentNullException(nameof(services));
        }

        AddHttpClient(services);

        var name = TypeNameHelper.GetTypeDisplayName(typeof(TClient), fullName: false);
        var builder = new DefaultHttpClientBuilder(services, name);
        builder.AddTypedClient<TClient>();
        return builder;
    }

HttpClientBuilderExtensions

        public static IHttpClientBuilder AddTypedClient<TClient>(this IHttpClientBuilder builder)
        where TClient : class
    {
        if (builder == null)
        {
            throw new ArgumentNullException(nameof(builder));
        }

        builder.Services.AddTransient<TClient>(s =>
        {
            var httpClientFactory = s.GetRequiredService<IHttpClientFactory>();
            var httpClient = httpClientFactory.CreateClient(builder.Name);

            var typedClientFactory = s.GetRequiredService<ITypedHttpClientFactory<TClient>>();
            return typedClientFactory.CreateClient(httpClient);
        });

        return builder;
    }

因此，您可以尝试将CancellationTokenSource注册为Transient。

services.AddTransient<CancellationTokenSource>();