无法访问HttpClient的DelegatingHandler类中的已处置对象

Question

我正在将TokenHttpHandler用于HttpClient。看起来像这样。

public class TokenHttpHandler : DelegatingHandler
  {
    private readonly ITokenCache tokenCache;
    private readonly IHttpProxyClientService proxyClientService;

    public TokenHttpHandler(IHttpProxyClientService proxyClientService, ITokenCache tokenCache)
    {
      this.proxyClientService = proxyClientService;
      this.tokenCache = tokenCache;

      var useProxy = AppSettingsProvider.AppSettings.Proxy.UseProxy;
      InnerHandler = useProxy ? proxyClientService.GetProxyHandler() : new HttpClientHandler();
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
      var response = await SetAuthHeaderAndSendAsync(request, cancellationToken, false).ConfigureAwait(false);
      if (response.StatusCode == HttpStatusCode.Unauthorized)
      {
        response = await SetAuthHeaderAndSendAsync(request, cancellationToken, true);
      }
      return response;
    }

    private async Task<HttpResponseMessage> SetAuthHeaderAndSendAsync(HttpRequestMessage request, CancellationToken cancellationToken, bool forceTokenRefresh)
    {      
      request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", await tokenCache.GetAccessToken(forceTokenRefresh).ConfigureAwait(false));
      return await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
    }
  }

在使用autofac的ASP.NET核心应用程序中，我注册了类似的类型：

// Token cache
      builder.RegisterType<TokenCache>().As<ITokenCache>()
        .WithParameter("scope", "Scope")
        .SingleInstance();

      builder.RegisterType<TokenHttpHandler>()
        .InstancePerLifetimeScope();

      builder.RegisterType<ProductionHttpClient>()
        .As<HttpClient>()
        .InstancePerLifetimeScope();

问题是因为只有代码才行：

返回等待基地。SendAsync（request，cancelToken）.ConfigureAwait（false）;

我收到错误：

“无法访问已处置的对象。\ r \ n对象名称：'TokenHttpHandler'。”这是怎么回事？

我在这里想念什么？

Answer 1

公共IServiceProvider ConfigureServices（IServiceCollection服务）加载项

services.AddScoped<HttpClient>();
services
   .AddHttpClient<ProductionHttpClient>()
   .AddHttpMessageHandler<TokenHttpHandler>();