当Startup.cs在不同的程序集中时，ASP.NET Core Web API返回404

问题描述

我具有.net核心Web API，并且在不同的程序集中隔离 Startup.cs 时，所有API均返回404，如果我将 Startup.cs 返回相同的程序集在存在控制器的地方，它们可以再次工作.

I have .net core web API and when I isolated Startup.cs in different assembly all APIs return 404 and if I return Startup.cs back to the same assembly where controllers exist, they work again.

这是我的Web API的 Program.cs :

Here is my Program.cs of my web API:

public class Program
{
    public static void Main(string[] args)
    {
      CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
      WebHost.CreateDefaultBuilder(args)
       .UseStartup<Startup>()
       .ConfigureAppConfiguration((hostContext, configApp) =>
       {
           configApp.SetBasePath(Directory.GetCurrentDirectory());
           configApp.AddJsonFile("appsettings.json", false, true);
           configApp.AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", false, true);
       });
}

还有我的Startup.cs:

And my Startup.cs :

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {

        services.AddMvc()
                .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
                .AddDataAnnotationsLocalization(options =>
                {
                    options.DataAnnotationLocalizerProvider = (type, factory) =>
                        factory.Create(typeof(ValidationMessages));
                });
    }


    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {

        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseMvc();
    }
}

因此，我需要将启动类放在不同的程序集中，然后在多个Web API项目中使用它

So I need to put startup class in a different assembly and then use it inside multiple Web API projects

推荐答案

用以下几行替换.UseStartup:

.UseStartup<Application.AppComponents.Startup>()
.UseSetting(WebHostDefaults.ApplicationKey, typeof(Program).GetTypeInfo().Assembly.FullName)

Application.AppComponents.Startup是类库中启动文件的名称空间.

Where Application.AppComponents.Startup is the namespace of your startup file in the class library.

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