ASP.NET Core 运行原理剖析2:Startup 和 Middleware(中间件)

Startup Class

构造 -> configureServices->configure

1、Startup Constructor（构造函数）

IHostingEnvironment

applicationName

applicationVersion

IHostingEnvironment

var builder = new ConfigurationBuilder()
                           .SetBasePath(env.ContentRootPath)
                            .AddJsonFile("appsettings.json");                     var configuration = builder.Build();                     var connStr = configuration.GetSection("Data:DefaultConnection:ConnectionString").Value;

{
   "Data": {
       "DefaultConnection": {
           "ConnectionString": "Server=(localdb)\\MSSQLLocalDB;Database=_CHANGE_ME;Trusted_Connection=True;"
       }
   }}

ILoggerFactory

public Startup(IHostingEnvironment env, ILoggerFactory logger) {         var log = logger.CreateLogger("default");
        logger.AddConsole();
        log.LogInformation("start configure");
}

2、ConfigureServices

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace WebApplication1{   public interface IFoo
   {        string GetFoo();
   }
}

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace WebApplication1{    public class Foo : IFoo
   {        public string GetFoo()        {            return "foo";
       }
   }
}

public void ConfigureServices(IServiceCollection services)       {
          services.AddTransient<IFoo, Foo>();
      }

RequestServices.GetRequiredService<IFoo>()

app.Run((context) =>
          {               var str = context.RequestServices.GetRequiredService<IFoo>().GetFoo();               return context.Response.WriteAsync(str);
          });

public void ConfigureServices(IServiceCollection services){    // Add framework services.
   services.AddDbContext<ApplicationDbContext>(options =>
       options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

   services.AddIdentity<ApplicationUser, IdentityRole>()
       .AddEntityFrameworkStores<ApplicationDbContext>()
       .AddDefaultTokenProviders();

   services.AddMvc();    // Add application services.
    services.AddTransient<IFoo, Foo>();

}

3、Configure方法

IApplicationBuilder

public void Configure(IApplicationBuilder app){
   app.Run((context) => context.Response.WriteAsync("Hello World!"));
}

IHostingEnvironment

ILoggerFactory

Middleware

1、中间件注册

public static IApplicationBuilder Use(this IApplicationBuilder app, Func<HttpContext, Func<Task>, Task> middleware); public static void Run(this IApplicationBuilder app, RequestDelegate handler);

app.Run((context) => context.Response.WriteAsync("Hello World!"));

app.Run((context) => context.Response.WriteAsync("Hello World 1!"));

app.Use((context, next) =>
                    {
                            context.Response.WriteAsync("ok");                             return next();
                    });
app.Use((context, next) =>
                    {                             return context.Response.WriteAsync("ok");
                    });

app.Map("/admin", builder =>
                   {
                           builder.Use((context, next) => context.Response.WriteAsync("admin"));
                   });

2、常用中间件