Middleware In ASP.NET Core

中间件简介

ASP.NET Core 由很多中间件构成，实现了一个HTTP请求管道（pipeline）。

Request的Response的管道可以看成一个Push Stack 和 Pop Stack。

在Startup.cs的Configure方法中配置中间件。

实现一个中间件

1. 构造函数RequestDelegate参数；
2. Invoke(HttpContext context)方法；

using Microsoft.AspNetCore.Http;
using System.Threading.Tasks;
using System.Diagnostics;
using System.IO;

namespace WebAppWithIndividualUserAccounts
{
    public class ResponseTime
    {
        RequestDelegate _next;
        public ResponseTime(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            var sw = new Stopwatch();
            sw.Start();

            await _next(context);

            var isHtml = context.Response.ContentType?.ToLower().Contains("text/html");
            if (context.Response.StatusCode == 200 && isHtml.GetValueOrDefault())
            {
                var body = context.Response.Body;

                using (var streamWriter = new StreamWriter(body))
                {
                    var txtHtml = $"<footer><div id='process'>Response Time {sw.ElapsedMilliseconds} milliseconds.</div></footer>";

                    streamWriter.Write(txtHtml);
                }
            }
        }
    }
}

注册一个中间件

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            app.UseMiddleware<ResponseTime>();
            //......

运行

即可看到效果