Net Core中间件封装原理示例demo解析

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/ITzhongzi/article/details/80883935

目的： 创建一个在接收到请求之后，将请求的地址打印在后台服务器窗口上的中间件

注意： 该项目是通过 vs2017 新建项目-> Net Core -> ASP.NET Web应用程序 -> 空 模板 初始化 

1. 创建一个 RequestExtensions.cs 的文件，这个文件用来扩展增加一个中间件

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

namespace MiddlelewareDemo
{
    public static class RequestIpExtensions
    {
        public static IApplicationBuilder UseRequestIp(this IApplicationBuilder builder)
        {
            return builder.UseMiddleware<RequestIPMiddleware>();
        }
    }
}

1. 创建一个 RequestIPMiddleware.cs 的文件,这个文件是中间件的具体实现(获取远程访问的地址，并将该地址输出到服务器控制台上)

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

namespace MiddlelewareDemo
{
    public class RequestIPMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger _logger;

        public RequestIPMiddleware(RequestDelegate next, ILoggerFactory loggerFactory)
        {
            _next = next;
            _logger = loggerFactory.CreateLogger<RequestIPMiddleware>();
        }

        public async Task Invoke(HttpContext context)
        {
            _logger.LogInformation("User Ip: " + context.Connection.RemoteIpAddress.ToString());
            await _next.Invoke(context);
        }
    }
}

1. 接下来我们在 Startup.cs 中使用该中间件，用 app.UseRequestIp(); 调用。

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 MiddlelewareDemo
{
    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.UseDefaultFiles();
            app.UseRequestIp();

            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello 0 World!");
            });
        }
    }
}

1. Program.cs文件的代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace MiddlelewareDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .Build();
    }
}

运行效果：

我们看到 中间件调用成功，在浏览器访问的时候在后台成功打印出了 IP xxxxx。