c# - ASP.NET Core Web API - JWT 消息处理程序 - 无注册类型错误

Question

我为我的 Web API 项目创建了一个 JWT token 处理程序。这个想法是这个 API 只是一个通往其他 API 的网关，并且一个 token 在它们之间共享。因此，当调用我的 API 并将调用转发给另一个时，我想自动转发附加到初始请求的 JWT。
我制作了一个自定义 MessageHandler ，如下所示:

public class JwtTokenHeaderHandler : DelegatingHandler
{
    private readonly HttpContext httpContext;
   public JwtTokenHeaderHandler(HttpContext httpContext)
   {
       this.httpContext = httpContext;
   }
   protected override async Task<HttpResponseMessage> SendAsync(
       HttpRequestMessage request,
       CancellationToken cancellationToken)
   {
       string savedToken = await this.httpContext.GetTokenAsync("access_token");
       request.Headers.Add("bearer", savedToken);
       return await base.SendAsync(request, cancellationToken);
   } 
}

然后我在 Startup 中将其注册为服务，如下所示:

services.AddTransient<HttpMessageHandler>(p => p.GetRequiredService<JwtTokenHeaderHandler>());

IHttpClientBuilder serviceClientBuilder = services.AddHttpClient<IService, Service>(client =>
{
    client.BaseAddress = new Uri(this.Configuration.GetValue<string>("ServiceURL"));
}).AddHttpMessageHandler<JwtTokenHeaderHandler>();

应用程序一直运行直到发出请求，然后出现此异常:

An unhandled exception has occurred while executing the request.

System.InvalidOperationException: No service for type 'Application.API1.JwtTokenHeaderHandler' has been registered.at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__4`1.b__4_1(HttpMessageHandlerBuilder b)at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass17_0.g__Configure|0(HttpMessageHandlerBuilder b)at Microsoft.Extensions.Http.LoggingHttpMessageHandlerBuilderFilter.<>c__DisplayClass3_0.b__0(HttpMessageHandlerBuilder builder)

Answer 1

一、注入(inject)HttpContext直接会引起问题。使用IHttpContextAccessor并在 Send 方法中访问上下文。

public class JwtTokenHeaderHandler : DelegatingHandler {
    private readonly IHttpContextAccessor accessor;

    public JwtTokenHeaderHandler(IHttpContextAccessor accessor) {
        this.accessor = accessor;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) {
        string savedToken = await accessor.HttpContext.GetTokenAsync("access_token");
        request.Headers.Add("bearer", savedToken);
        return await base.SendAsync(request, cancellationToken);
    } 
}

下一个 GetRequiredService当请求的服务未在集合中注册时会引发该异常，因此请确保将处理程序注册到容器中
笔记

The handler type must be registered as a transient service.

引用 AddHttpMessageHandler<THandler>(IHttpClientBuilder)

services.AddTransient<JwtTokenHeaderHandler>();

这样 JwtTokenHeaderHandler可以根据服务提供商的要求解决

services.AddTransient<HttpMessageHandler>(p => p.GetRequiredService<JwtTokenHeaderHandler>());
services.AddHttpClient<IService, Service>(client => {
    client.BaseAddress = new Uri(this.Configuration.GetValue<string>("ServiceURL"));
}).AddHttpMessageHandler<JwtTokenHeaderHandler>();