dotNetCore v2-四大组件

一：了解asp.net core 中的几大部件

1. 从本质上来看, asp.net core 也就是 console程序台程序，所以花了很大的篇幅去介绍console程序。

（WebHost，Startup，launchSettings，wwwroot）

二：WebHost

WebHost => Socket实现的web服务的加强版。。

1. WebHost使用了建造者模式。

2. CreateDefaultBuilder 到底干了什么？

<1> 添加web服务器支持IIS 和 Kestrel

<2> 添加configuration配置系统

支持 appsettings.json && 多环境的 appsettings.env.json
   支持 commandline

<3> 添加日志系统

支持输出到Console和Debug窗口。

       //IL_000d: Unknown result type (might be due to invalid IL or missing references)
       //IL_0017: Expected O, but got Unknown
       return WebHostBuilderExtensions.UseDefaultServiceProvider(WebHostBuilderIISExtensions.UseIISIntegration(WebHostBuilderExtensions.ConfigureLogging(WebHostBuilderKestrelExtensions.UseKestrel((IWebHostBuilder)new WebHostBuilder()).UseContentRoot(Directory.GetCurrentDirectory()).ConfigureAppConfiguration(delegate(WebHostBuilderContext hostingContext, IConfigurationBuilder config)
       {
           IHostingEnvironment hostingEnvironment = hostingContext.HostingEnvironment;
           JsonConfigurationExtensions.AddJsonFile(JsonConfigurationExtensions.AddJsonFile(config, "appsettings.json", true, true), $"appsettings.{hostingEnvironment.EnvironmentName}.json", true, true);
           if (hostingEnvironment.IsDevelopment())
           {
               Assembly assembly = Assembly.Load(new AssemblyName(hostingEnvironment.ApplicationName));
               if (assembly != null)
               {
                   UserSecretsConfigurationExtensions.AddUserSecrets(config, assembly, true);
               }
           }
           EnvironmentVariablesExtensions.AddEnvironmentVariables(config);
           if (args != null)
           {
               CommandLineConfigurationExtensions.AddCommandLine(config, args);
           }
       }), (Action<WebHostBuilderContext, ILoggingBuilder>)delegate(WebHostBuilderContext hostingContext, ILoggingBuilder logging)
       {
           LoggingBuilderExtensions.AddConfiguration(logging, hostingContext.Configuration.GetSection("Logging"));
           ConsoleLoggerExtensions.AddConsole(logging);
           DebugLoggerFactoryExtensions.AddDebug(logging);
       })), (Action<WebHostBuilderContext, ServiceProviderOptions>)delegate(WebHostBuilderContext context, ServiceProviderOptions options)
       {
           options.set_ValidateScopes(context.HostingEnvironment.IsDevelopment());
       });

在Build方法中做了所有的初始化操作

《1》初始化了一个IOC容器

《2》初始化到了WebHost

《3》Startup 已单例的方式添加到了IOC容器

我们也可以继承 IStartup 。。。

总结：WebHost在启动之前做了无数的事情。。。

三：Startup

1. ConfigureServices

给程序员添加一些服务的代码区。

比如AddMvc查看mvc源码

internal static void AddViewServices(IServiceCollection services)
{
DataProtectionServiceCollectionExtensions.AddDataProtection(services);
AntiforgeryServiceCollectionExtensions.AddAntiforgery(services);
EncoderServiceCollectionExtensions.AddWebEncoders(services);
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IConfigureOptions<MvcViewOptions>, MvcViewOptionsSetup>());
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IPostConfigureOptions<MvcViewOptions>, MvcViewOptionsConfigureCompatibilityOptions>());
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IConfigureOptions<MvcOptions>, TempDataMvcOptionsSetup>());
ServiceCollectionDescriptorExtensions.TryAddSingleton<ICompositeViewEngine, CompositeViewEngine>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IActionResultExecutor<ViewResult>, ViewResultExecutor>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IActionResultExecutor<PartialViewResult>, PartialViewResultExecutor>(services);
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IControllerPropertyActivator, ViewDataDictionaryControllerPropertyActivator>());
ServiceCollectionDescriptorExtensions.TryAddTransient<IHtmlHelper, HtmlHelper>(services);
ServiceCollectionDescriptorExtensions.TryAddTransient(services, typeof(IHtmlHelper<>), typeof(HtmlHelper<>));
ServiceCollectionDescriptorExtensions.TryAddSingleton<IHtmlGenerator, DefaultHtmlGenerator>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ExpressionTextCache>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IModelExpressionProvider, ModelExpressionProvider>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ValidationHtmlAttributeProvider, DefaultValidationHtmlAttributeProvider>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IJsonHelper, JsonHelper>(services);
ServiceCollectionDescriptorExtensions.TryAdd(services, ServiceDescriptor.Singleton<JsonOutputFormatter>(delegate (IServiceProvider serviceProvider) {
return new JsonOutputFormatter(ServiceProviderServiceExtensions.GetRequiredService<IOptions<MvcJsonOptions>>(serviceProvider).get_Value().get_SerializerSettings(), ServiceProviderServiceExtensions.GetRequiredService<ArrayPool<char>>(serviceProvider));
}));
ServiceCollectionDescriptorExtensions.TryAddSingleton<IViewComponentSelector, DefaultViewComponentSelector>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IViewComponentFactory, DefaultViewComponentFactory>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IViewComponentActivator, DefaultViewComponentActivator>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IViewComponentDescriptorCollectionProvider, DefaultViewComponentDescriptorCollectionProvider>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IActionResultExecutor<ViewComponentResult>, ViewComponentResultExecutor>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ViewComponentInvokerCache>(services);
ServiceCollectionDescriptorExtensions.TryAddTransient<IViewComponentDescriptorProvider, DefaultViewComponentDescriptorProvider>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<IViewComponentInvokerFactory, DefaultViewComponentInvokerFactory>(services);
ServiceCollectionDescriptorExtensions.TryAddTransient<IViewComponentHelper, DefaultViewComponentHelper>(services);
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IApplicationModelProvider, TempDataApplicationModelProvider>());
ServiceCollectionDescriptorExtensions.TryAddEnumerable(services, ServiceDescriptor.Transient<IApplicationModelProvider, ViewDataAttributeApplicationModelProvider>());
ServiceCollectionDescriptorExtensions.TryAddSingleton<SaveTempDataFilter>(services);
ServiceCollectionDescriptorExtensions.TryAddTransient<ControllerSaveTempDataPropertyFilter>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ITempDataProvider, CookieTempDataProvider>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ValidateAntiforgeryTokenAuthorizationFilter>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<AutoValidateAntiforgeryTokenAuthorizationFilter>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ITempDataDictionaryFactory, TempDataDictionaryFactory>(services);
ServiceCollectionDescriptorExtensions.TryAddSingleton<ArrayPool<ViewBufferValue>>(services, ArrayPool<ViewBufferValue>.get_Shared());
ServiceCollectionDescriptorExtensions.TryAddScoped<IViewBufferScope, MemoryPoolViewBufferScope>(services);
}