中间件执行顺序不正确的 autofac webapi owin 集成问题

Question

我对 Autofac 示例感到困惑：WebApiExample.OwinSelfHost，启动 class 如下：

    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            // In OWIN you create your own HttpConfiguration rather than
            // re-using the GlobalConfiguration.
            var config = new HttpConfiguration();

            config.Routes.MapHttpRoute(
                "DefaultApi",
                "api/{controller}/{id}",
                new { id = RouteParameter.Optional });

            var builder = new ContainerBuilder();

            // Register Web API controller in executing assembly.
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

            // OPTIONAL - Register the filter provider if you have custom filters that need DI.
            // Also hook the filters up to controllers.
            builder.RegisterWebApiFilterProvider(config);
            builder.RegisterType<CustomActionFilter>()
                .AsWebApiActionFilterFor<TestController>()
                .InstancePerRequest();

            // Register a logger service to be used by the controller and middleware.
            builder.Register(c => new Logger()).As<ILogger>().InstancePerRequest();

            // Autofac will add middleware to IAppBuilder in the order registered.
            // The middleware will execute in the order added to IAppBuilder.
            builder.RegisterType<FirstMiddleware>().InstancePerRequest();
            builder.RegisterType<SecondMiddleware>().InstancePerRequest();

            // Create and assign a dependency resolver for Web API to use.
            var container = builder.Build();
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);

            // The Autofac middleware should be the first middleware added to the IAppBuilder.
            // If you "UseAutofacMiddleware" then all of the middleware in the container
            // will be injected into the pipeline right after the Autofac lifetime scope
            // is created/injected.
            //
            // Alternatively, you can control when container-based
            // middleware is used by using "UseAutofacLifetimeScopeInjector" along with
            // "UseMiddlewareFromContainer". As long as the lifetime scope injector
            // comes first, everything is good.
            app.UseAutofacMiddleware(container);

            // Again, the alternative to "UseAutofacMiddleware" is something like this:
            // app.UseAutofacLifetimeScopeInjector(container);
            // app.UseMiddlewareFromContainer<FirstMiddleware>();
            // app.UseMiddlewareFromContainer<SecondMiddleware>();

            // Make sure the Autofac lifetime scope is passed to Web API.
            app.UseAutofacWebApi(config);
            app.UseWebApi(config);
        }
    }

FirstMiddleware 和 SecondMiddleware 代码如下：

    public class FirstMiddleware : OwinMiddleware
    {
        private readonly ILogger _logger;

        public FirstMiddleware(OwinMiddleware next, ILogger logger) : base(next)
        {
            this._logger = logger;
        }

        public override async Task Invoke(IOwinContext context)
        {
            this._logger.Write("Inside the 'Invoke' method of the '{0}' middleware.", GetType().Name);

            await Next.Invoke(context);
        }
    }

    public class SecondMiddleware : OwinMiddleware
    {
        private readonly ILogger _logger;

        public SecondMiddleware(OwinMiddleware next, ILogger logger) : base(next)
        {
            this._logger = logger;
        }

        public override async Task Invoke(IOwinContext context)
        {
            this._logger.Write("Inside the 'Invoke' method of the '{0}' middleware.", GetType().Name);

            await Next.Invoke(context);
        }
    }

根据评论，中间件注册顺序很重要。首先是 FirstMiddleware，然后是 SecondMiddleware。但输出是第二个中间件首先被调用。 the program logs output here

订单有什么问题？这是autofac官方的例子WebApiExample.OwinSelfHost

Answer 1

看来您发现了一个错误！ I've filed an issue about it on your behalf. 您可以在那里阅读更多关于它的技术细节，但简而言之，多年来我们已经更改了一些 Autofac 内部结构以支持 .NET Core，这看起来像是我们错过的东西。

解决此问题之前的解决方法是以相反的顺序注册中间件，这不是很好，因为一旦应用修复，您将不得不将它们撤回。 :(

中间件执行顺序不正确的 autofac webapi owin 集成问题

autofac webapi owin integration problems with middleware exection order not correct

autofac