C#中間件如何集成身份驗證框架

在C#中，我們可以使用ASP.NET Core來創建一個中間件，并集成身份驗證框架。ASP.NET Core是一個跨平臺的開源框架，用于構建現代云應用程序。它提供了許多內置的身份驗證和授權功能，如JWT、OAuth 2.0等。

以下是一個簡單的示例，展示了如何在ASP.NET Core中創建一個中間件，并集成IdentityServer4作為身份驗證框架：

1. 首先，確保已安裝以下NuGet包：

   • Microsoft.AspNetCore.Authentication
   • IdentityServer4.AccessTokenValidation

2. 在Startup.cs文件中，配置IdentityServer4作為身份驗證框架：

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;
using Microsoft.Extensions.Hosting;

namespace MiddlewareAuthentication
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddAuthentication("Bearer")
                .AddIdentityServerAuthentication("Bearer", options =>
                {
                    options.Authority = "http://localhost:5000"; // IdentityServer4的地址
                    options.RequireHttpsMetadata = false;
                    options.ApiName = "api1"; // 在IdentityServer4中注冊的API名稱
                });
        }

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

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

3. 創建一個中間件類，例如AuthenticationMiddleware.cs：

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

namespace MiddlewareAuthentication
{
    public class AuthenticationMiddleware
    {
        private readonly RequestDelegate _next;

        public AuthenticationMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task InvokeAsync(HttpContext context)
        {
            if (!context.User.Identity.IsAuthenticated)
            {
                context.Response.StatusCode = 401;
                await context.Response.WriteAsync("Unauthorized");
                return;
            }

            await _next(context);
        }
    }
}

4. 在Startup.cs文件中，將中間件添加到請求管道中：

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ...

    app.UseMiddleware<AuthenticationMiddleware>();

    // ...
}

現在，當客戶端請求API時，中間件會檢查請求是否包含有效的訪問令牌。如果沒有，它將返回401 Unauthorized響應。如果有效，請求將繼續傳遞給下一個中間件或控制器。