dotNetCore v3-创建中间件

创建空的.netcore webproject

/*****************************MyStaticFileExtensions.cs*********************************/

using Microsoft.AspNetCore.Builder;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication2
{
    public static class MyStaticFileExtensions
    {
        public static IApplicationBuilder UseMyStaticFile(this IApplicationBuilder app)
        {
            if (app == null)
            {
                throw new ArgumentNullException("app");
            }
            return app.UseMiddleware<MyStaticFileMiddleware>(Array.Empty<object>());
        }
    }
}

/**********************************MyStaticFileMiddleware.cs************************************/

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication2
{
    public class MyStaticFileMiddleware
    {
        private readonly RequestDelegate _next;

        public MyStaticFileMiddleware(RequestDelegate next)
        {
            this._next = next;
        }
        /// <summary>
        /// Invoke执行
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public Task Invoke(HttpContext context)
        {
            var path = context.Request.Path.Value.TrimStart('/');
            if (path.Contains(".jpg"))
            {
                return context.Response.SendFileAsync(path);
            }            

            var task = _next(context);
            return task;
        }
    }
}
/*************************Startup.cs**************************************/

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 WebApplication2
{
    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.UseMyStaticFile();

            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World!");
            });
        }
    }
}