ASP.NET Core 学习笔记（http请求处理）

1、http处理请求

2、webhost 配置与启动

1)自定义配置（json ,commandLine）

  public class mycly
    {
        public string cly { get; set; }
        public string name { get; set; }

    }


   public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration(configureDelegate =>
            {
                configureDelegate.AddJsonFile("cly.json", true, true)
                .AddCommandLine(args);
            })
            .UseUrls("http://localhost:5300")
                .UseStartup<Startup>();

            services.Configure<mycly>(Configuration);

       private readonly IOptionsSnapshot<mycly> _options;
        public HomeController(IOptionsSnapshot<mycly> options)
        {
            _options = options;
        }
        public IActionResult Index()
        {
            return Content(_options.Value.cly + _options.Value.name);
        }

 　　

3、IHostEnvironment 和IApplicationLifetime

     applicationLifetime.ApplicationStarted.Register(() =>
            {
                Console.WriteLine("Started");
            });
            applicationLifetime.ApplicationStopped.Register(() =>
            {
                Console.WriteLine("Stopped");
            });
            applicationLifetime.ApplicationStopping.Register(() =>
            {
                Console.WriteLine("Stopping");
            });
            app.Run(async context =>
            {
                await context.Response.WriteAsync(env.ApplicationName);
                await context.Response.WriteAsync(env.ContentRootPath);
                await context.Response.WriteAsync(env.EnvironmentName);
                await context.Response.WriteAsync(env.WebRootPath);

            });

<DotNetCliToolReference Include="Microsoft.DotNet.Watcher.Tools" Version="2.0.0" />

4、Middleware 管道 （主要处理类RequestDelegate）

https://www.cnblogs.com/Vam8023/p/10700254.html

源码： HttpAbstractions项目 ；相关主要类（ApplicationBuilder.cs UseExtensions.cs UseMiddlewareExtensions.cs MiddlewareFactory.cs）

      /// <summary>
        /// Adds a middleware type to the application's request pipeline.
        /// </summary>
        /// <typeparam name="TMiddleware">The middleware type.</typeparam>
        /// <param name="app">The <see cref="IApplicationBuilder"/> instance.</param>
        /// <param name="args">The arguments to pass to the middleware type instance's constructor.</param>
        /// <returns>The <see cref="IApplicationBuilder"/> instance.</returns>
        public static IApplicationBuilder UseMiddleware<TMiddleware>(this IApplicationBuilder app, params object[] args)
        {
            return app.UseMiddleware(typeof(TMiddleware), args);
        }

        /// <summary>
        /// Adds a middleware type to the application's request pipeline.
        /// </summary>
        /// <param name="app">The <see cref="IApplicationBuilder"/> instance.</param>
        /// <param name="middleware">The middleware type.</param>
        /// <param name="args">The arguments to pass to the middleware type instance's constructor.</param>
        /// <returns>The <see cref="IApplicationBuilder"/> instance.</returns>
        public static IApplicationBuilder UseMiddleware(this IApplicationBuilder app, Type middleware, params object[] args)
        {
            if (typeof(IMiddleware).GetTypeInfo().IsAssignableFrom(middleware.GetTypeInfo()))
            {
                // IMiddleware doesn't support passing args directly since it's
                // activated from the container
                if (args.Length > 0)
                {
                    throw new NotSupportedException(Resources.FormatException_UseMiddlewareExplicitArgumentsNotSupported(typeof(IMiddleware)));
                }

                return UseMiddlewareInterface(app, middleware);
            }

            var applicationServices = app.ApplicationServices;
            return app.Use(next =>
            {
                var methods = middleware.GetMethods(BindingFlags.Instance | BindingFlags.Public);
                var invokeMethods = methods.Where(m =>
                    string.Equals(m.Name, InvokeMethodName, StringComparison.Ordinal)
                    || string.Equals(m.Name, InvokeAsyncMethodName, StringComparison.Ordinal)
                    ).ToArray();

                if (invokeMethods.Length > 1)
                {
                    throw new InvalidOperationException(Resources.FormatException_UseMiddleMutlipleInvokes(InvokeMethodName, InvokeAsyncMethodName));
                }

                if (invokeMethods.Length == 0)
                {
                    throw new InvalidOperationException(Resources.FormatException_UseMiddlewareNoInvokeMethod(InvokeMethodName, InvokeAsyncMethodName, middleware));
                }

                var methodInfo = invokeMethods[0];
                if (!typeof(Task).IsAssignableFrom(methodInfo.ReturnType))
                {
                    throw new InvalidOperationException(Resources.FormatException_UseMiddlewareNonTaskReturnType(InvokeMethodName, InvokeAsyncMethodName, nameof(Task)));
                }

                var parameters = methodInfo.GetParameters();
                if (parameters.Length == 0 || parameters[0].ParameterType != typeof(HttpContext))
                {
                    throw new InvalidOperationException(Resources.FormatException_UseMiddlewareNoParameters(InvokeMethodName, InvokeAsyncMethodName, nameof(HttpContext)));
                }

                var ctorArgs = new object[args.Length + 1];
                ctorArgs[0] = next;
                Array.Copy(args, 0, ctorArgs, 1, args.Length);
                var instance = ActivatorUtilities.CreateInstance(app.ApplicationServices, middleware, ctorArgs);
                if (parameters.Length == 1)
                {
                    return (RequestDelegate)methodInfo.CreateDelegate(typeof(RequestDelegate), instance);
                }

                var factory = Compile<object>(methodInfo, parameters);

                return context =>
                {
                    var serviceProvider = context.RequestServices ?? applicationServices;
                    if (serviceProvider == null)
                    {
                        throw new InvalidOperationException(Resources.FormatException_UseMiddlewareIServiceProviderNotAvailable(nameof(IServiceProvider)));
                    }

                    return factory(instance, context, serviceProvider);
                };
            });
        }

        private static IApplicationBuilder UseMiddlewareInterface(IApplicationBuilder app, Type middlewareType)
        {
            return app.Use(next =>
            {
                return async context =>
                {
                    var middlewareFactory = (IMiddlewareFactory)context.RequestServices.GetService(typeof(IMiddlewareFactory));
                    if (middlewareFactory == null)
                    {
                        // No middleware factory
                        throw new InvalidOperationException(Resources.FormatException_UseMiddlewareNoMiddlewareFactory(typeof(IMiddlewareFactory)));
                    }

                    var middleware = middlewareFactory.Create(middlewareType);
                    if (middleware == null)
                    {
                        // The factory returned null, it's a broken implementation
                        throw new InvalidOperationException(Resources.FormatException_UseMiddlewareUnableToCreateMiddleware(middlewareFactory.GetType(), middlewareType));
                    }

                    try
                    {
                        await middleware.InvokeAsync(context, next);
                    }
                    finally
                    {
                        middlewareFactory.Release(middleware);
                    }
                };
            });
        }

自定义中间件时 通过查看UseMiddlewareExtensions.cs ，即可了解使用管道具体做了些什么。（IMiddleware doesn't support passing args directly since it's activated from the container)

5、MVC路由及RoutingMiddleware 源码解析

MvcApplicationBuilderExtensions.cs ->RoutingBuilderExtensions.cs (UseRouter,builder.UseMiddleware<RouterMiddleware>(router))

MapRouteRouteBuilderExtensions.cs, RouteBase.cs, Route.cs, RouteBuilder.cs,RouteCollection.cs(RouteAsync),RouterMiddleware.cs