ASP .NET Core-中间件

1 与ASP .NET MVC

• ASP .NET MVC 就是UrlRoutingModule 实现了url请求的拦截。
• ASP .NET Core 的Pipeline 更加轻量化，模块化
• 改变了HttpModule的事件模式，单链表（递归） next方法

2 理解

1.png

1. RequestDelegate
2. ApplicationBuilder
   _compennents
   Run 方法
   2.png

调用Use

3.png

3 使用

  // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.Use(async (context, next) =>
            {
                await context.Response.WriteAsync(" First Middleware Output </br>");
                //此处执行 才能不中断管道
                await next.Invoke();
            });
            app.Use(next =>
            {
                return (context) =>
                {
                     context.Response.WriteAsync(" Second Middleware Output </br>");
                    //此处执行 才能不中断管道
                    return next(context);
                };
            });
            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World! </br>");
            });
            
        }

4 实现自定义的Middleware

定义UserIpWhiteMiddleware

public class IpWhiteMiddleware
    {
        private readonly RequestDelegate _next;

        public IpWhiteMiddleware(RequestDelegate next)
        {
            this._next = next;
        }


        public Task Invoke(HttpContext context)
        {
            var whiteList = new List<string>() {"127.0.0.1", "::1" };
            var rqIp = context.Connection.RemoteIpAddress.ToString();
            if (!whiteList.Any(c=>c==rqIp))
            {
                return  context.Response.WriteAsync(" not in white ip list");
            }
            var task = this._next.Invoke(context);
            return task;
        }
    }

定义IApplicationBuilder的扩展方法

  public static class IpWhiteMiddlewareExtensions
    {
        public static IApplicationBuilder UserIpWhiteMiddleware(this IApplicationBuilder app)
        {
            return UseMiddlewareExtensions.UseMiddleware<IpWhiteMiddleware>(app, Array.Empty<object>());
        }
    }

Startup.cs使用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace AspNetCoreStudy.Middleware
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.UserIpWhiteMiddleware();
            
           
        }
    }
}