怎么在asp.net core的中间件中返回具体的页面

public class Startup
{
    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        // 生成 swagger 配置的 json 文件
        services.AddSwaggerGen(s =>
        {
            s.SwaggerDoc("v1", new OpenApiInfo
            {
                Contact = new OpenApiContact
                {
                    Name = "Danvic Wang",
                    Url = new Uri("https://yuiter.com"),
                },
                Description = "Template.API - ASP.NET Core 后端接口模板",
                Title = "Template.API",
                Version = "v1"
            });

            // 参数使用驼峰的命名方式
            s.DescribeAllParametersInCamelCase();
        });
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // 公开 swagger 生成的 json 文件节点
        app.UseSwagger();

        // 启用 swagger 可视化交互页面
        app.UseSwaggerUI(s =>
        {
            s.SwaggerEndpoint($"/swagger/v1/swagger.json",
                $"Swagger doc v1");
        });
    }
}

public async Task Invoke(HttpContext httpContext)
{
    var httpMethod = httpContext.Request.Method;
    var path = httpContext.Request.Path.Value;

    // If the RoutePrefix is requested (with or without trailing slash), redirect to index URL
    if (httpMethod == "GET" && Regex.IsMatch(path, $"^/?{Regex.Escape(_options.RoutePrefix)}/?$"))
    {
        // Use relative redirect to support proxy environments
        var relativeRedirectPath = path.EndsWith("/")
            ? "index.html"
            : $"{path.Split('/').Last()}/index.html";

        RespondWithRedirect(httpContext.Response, relativeRedirectPath);
        return;
    }

    if (httpMethod == "GET" && Regex.IsMatch(path, $"^/{Regex.Escape(_options.RoutePrefix)}/?index.html$"))
    {
        await RespondWithIndexHtml(httpContext.Response);
        return;
    }

    await _staticFileMiddleware.Invoke(httpContext);
}

public class SwaggerUIMiddleware
{
    private const string EmbeddedFileNamespace = "Swashbuckle.AspNetCore.SwaggerUI.node_modules.swagger_ui_dist";

    private readonly SwaggerUIOptions _options;
    private readonly StaticFileMiddleware _staticFileMiddleware;

    public SwaggerUIMiddleware(
        RequestDelegate next,
        IHostingEnvironment hostingEnv,
        ILoggerFactory loggerFactory,
        SwaggerUIOptions options)
    {
        _options = options ?? new SwaggerUIOptions();

        _staticFileMiddleware = CreateStaticFileMiddleware(next, hostingEnv, loggerFactory, options);
    }

    private StaticFileMiddleware CreateStaticFileMiddleware(
        RequestDelegate next,
        IHostingEnvironment hostingEnv,
        ILoggerFactory loggerFactory,
        SwaggerUIOptions options)
    {
        var staticFileOptions = new StaticFileOptions
        {
            RequestPath = string.IsNullOrEmpty(options.RoutePrefix) ? string.Empty : $"/{options.RoutePrefix}",
            FileProvider = new EmbeddedFileProvider(typeof(SwaggerUIMiddleware).GetTypeInfo().Assembly, EmbeddedFileNamespace),
        };

        return new StaticFileMiddleware(next, hostingEnv, Options.Create(staticFileOptions), loggerFactory);
    }
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    app.UseHttpsRedirection();

    app.UseRouting();

    app.UseAuthorization();

// Endpoint 路由规则设定
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });

    // 自定义中间件
    app.UseMiddleware<SampleUIMiddleware>();
}