asp.net-web-api - Ninject.ActivationException 仅在第一个 Web 请求时抛出(WebAPI 2、OWIN 3、Ninject 3)

Question

我正在尝试创建一个“准系统”Web API 项目，该项目使用 OWIN 中间件、Ninject 依赖注入(inject)，并最终托管在 IIS 中。我已按照文章“与 ASP.NET Web.API2、OWIN 和 Ninject 成为 friend ”中的说明进行操作，此处:http://www.alexzaitzev.pro/2014/11/webapi2-owin-and-ninject.html ，除了我使用了一个空的Web应用程序项目，并且在创建项目时没有勾选“包括Web API引用和文件夹”。

当我启动新 API 并发出页面请求时，我抛出以下 Ninject.ActivationException :

Server Error in '/' Application.

Error activating HttpConfiguration
More than one matching bindings are available.
Matching bindings:
 1) binding from HttpConfiguration to method
 2) binding from HttpConfiguration to constant value
Activation path:
 1) Request for HttpConfiguration

Suggestions:
 1) Ensure that you have defined a binding for HttpConfiguration only once.

当我刷新浏览器时，此异常消失。我真的不明白是什么导致了这个异常。从我的角度来看，由于对 OWIN 上下文中的 WebAPI 和 Ninject 缺乏经验，很难知道问题出在哪里。是和Ninject一起吗……？是在欧文吗...？是在 WebAPI 中吗？

这是我的 Startup.cs 文件的内容:

using System.Web.Http;
using LHD.API_2;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using Ninject.Web.Common.OwinHost;
using Ninject.Web.WebApi.OwinHost;
using Owin;

[assembly: OwinStartup(typeof(Startup))]

namespace LHD.API_2
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            HttpConfiguration config = new HttpConfiguration();

            // Web API configuration and services
            // Configure Web API to use only bearer token authentication.
            config.SuppressDefaultHostAuthentication();
            config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));

            // Web API routes
            config.MapHttpAttributeRoutes();
            config.Routes.MapHttpRoute("API Default", "api/1/{controller}/{action}/{id}", new { id = RouteParameter.Optional });

            app.UseNinjectMiddleware(() => NinjectConfig.CreateKernel.Value);
            app.UseNinjectWebApi(config);
        }
    }
}

这是我的 NinjectConfig.cs 文件的内容:

using System;
using System.Reflection;
using Ninject;

namespace LHD.API_2
{
    public static class NinjectConfig
    {
        public static Lazy<IKernel> CreateKernel = new Lazy<IKernel>(() =>
        {
            StandardKernel kernel = new StandardKernel();
            kernel.Load(Assembly.GetExecutingAssembly());

            RegisterServices(kernel);

            return kernel;
        });

        private static void RegisterServices(KernelBase kernel)
        {
            // TODO - put in registrations here...

            //kernel.Bind<IFakeService>().To<FakeService>();
        }
    }
}

这是我的packages.config的内容:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Microsoft.AspNet.WebApi" version="5.0.0" targetFramework="net451" />
  <package id="Microsoft.AspNet.WebApi.Client" version="5.2.3" targetFramework="net451" />
  <package id="Microsoft.AspNet.WebApi.Core" version="5.2.3" targetFramework="net451" />
  <package id="Microsoft.AspNet.WebApi.Owin" version="5.2.3" targetFramework="net451" />
  <package id="Microsoft.AspNet.WebApi.WebHost" version="5.0.0" targetFramework="net451" />
  <package id="Microsoft.Owin" version="3.0.1" targetFramework="net451" />
  <package id="Microsoft.Owin.Host.SystemWeb" version="3.0.1" targetFramework="net451" />
  <package id="Newtonsoft.Json" version="6.0.4" targetFramework="net451" />
  <package id="Ninject" version="3.2.0.0" targetFramework="net451" />
  <package id="Ninject.Extensions.ContextPreservation" version="3.2.0.0" targetFramework="net451" />
  <package id="Ninject.Extensions.NamedScope" version="3.2.0.0" targetFramework="net451" />
  <package id="Ninject.Web.Common" version="3.2.0.0" targetFramework="net451" />
  <package id="Ninject.Web.Common.OwinHost" version="3.2.3.0" targetFramework="net451" />
  <package id="Ninject.Web.WebApi" version="3.2.0.0" targetFramework="net451" />
  <package id="Ninject.Web.WebApi.OwinHost" version="3.2.4.0" targetFramework="net451" />
  <package id="Owin" version="1.0" targetFramework="net451" />
</packages>

...而且，为了完整起见，我的 web.config 的内容同样不引人注目:

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
    <system.web>
        <compilation debug="true" targetFramework="4.5.1" />
        <httpRuntime targetFramework="4.5.1" />
    </system.web>

    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="Microsoft.Owin" publicKeyToken="31bf3856ad364e35" culture="neutral" />
                <bindingRedirect oldVersion="0.0.0.0-3.0.1.0" newVersion="3.0.1.0" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="System.Web.Http" publicKeyToken="31bf3856ad364e35" culture="neutral" />
                <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="System.Web.Http.Owin" publicKeyToken="31bf3856ad364e35" culture="neutral" />
                <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
            </dependentAssembly>
            <dependentAssembly>
                <assemblyIdentity name="System.Net.Http.Formatting" publicKeyToken="31bf3856ad364e35" culture="neutral" />
                <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
            </dependentAssembly>
        </assemblyBinding>
    </runtime>
<system.webServer>
    <handlers>
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <remove name="OPTIONSVerbHandler" />
      <remove name="TRACEVerbHandler" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    </handlers>
  </system.webServer>
</configuration>

任何人都可以指出我做错了什么，或者更重要的是，我可以改变什么以使事情正常运行而不抛出异常？

Answer 1

您使用的是哪个版本的Ninject.Web.WebApi库？看起来两周前进行了更改以移动一些内容。在此更改之前(v3.2.3 及更早版本)，HttpConfiguration 绑定(bind)存在于 Ninject.Web.WebApi.OwinHost.OwinWebApiModule 和 Ninject.Web 的 2 个不同模块中.WebApi.WebApiModule。进行此更改后(新版本为 3.2.4)，此绑定(bind)仅发生一次。