在ASP.Net Core

Question

当我的应用程序启动时，我有一堆模块（module1，module2 ......）。对于每个模块，我都有一堆控制器操作：

/myModuleController/module1/action1
/myModuleController/module1/action2
/myModuleController/module2/action1
/myModuleController/module2/action2
…

由于用户可以为每个模块记录一次，因此我为每个模块部署了一个身份验证中间件，只需这样做：

app.UseWhen((context) => context.Request.Path.StartsWithSegments(urlPath), appbuilder =>
    {
        appbuilder.UseCookieAuthentication(new CookieAuthenticationOptions()
        {
            CookieName = cookieName,
            …
        });
    });

所以基本上，在url路径/myModuleController/module1上我有一个中间件加上它的cookie，另一个用于/myModuleController/module2 ...我觉得这有点不寻常但是它工作正常，我对这种行为感到满意。

问题出现了：我希望能够在运行时添加一个新模块，这意味着能够使用像app.UseWhen(url, app. UseCookieAuthentication(…))这样的代码部署新的中间件。我天真地尝试在负责添加模块的控制器中注入IApplicationBuilder app，但我得到了一个例外：

  

System.InvalidOperationException：无法解析类型＆＃39; Microsoft.AspNetCore.Builder.IApplicationBuilder＆＃39;的服务。在尝试激活＆＃39; AdminController＆＃39;

时

我的问题是：它应该有效吗？我一定是在某个地方弄错了？或者，你是否清楚我在这里尝试的东西没有机会工作？

您如何达到同样的要求？ 感谢。

Answer 1

首先，我们需要一项服务来保留运行时中间件配置

public class RuntimeMiddlewareService
{
    private Func<RequestDelegate, RequestDelegate> _middleware;

    private IApplicationBuilder _appBuilder;

    internal void Use(IApplicationBuilder app)
    => _appBuilder = app.Use(next => context => _middleware(next)(context));

    public void Configure(Action<IApplicationBuilder> action)
    {
        var app = _appBuilder.New();
        action(app);
        _middleware = next => app.Use(_ => next).Build();
    }
}

然后添加一些扩展方法以在Startup中使用它

public static class RuntimeMiddlewareExtensions
{
    public static IServiceCollection AddRuntimeMiddleware(this IServiceCollection services, ServiceLifetime lifetime = ServiceLifetime.Singleton)
    {
        services.Add(new ServiceDescriptor(typeof(RuntimeMiddlewareService), typeof(RuntimeMiddlewareService), lifetime));
        return services;
    }

    public static IApplicationBuilder UseRuntimeMiddleware(this IApplicationBuilder app, Action<IApplicationBuilder> defaultAction = null)
    {
        var service = app.ApplicationServices.GetRequiredService<RuntimeMiddlewareService>();
        service.Use(app);
        if (defaultAction != null)
        {
            service.Configure(defaultAction);
        }
        return app;
    }
}

然后修改您的Startup

添加到ConfigureServices：

services.AddRuntimeMiddleware(/* ServiceLifetime.Scoped could be specified here if needed */);

添加到运行时指定的中间件应位于Configure内部的位置。

app.UseRuntimeMiddleware(runtimeApp =>
{
    //runtimeApp.Use...
    //Configurations here could be replaced during the runtime.
});

最后，您可以从应用程序的其他部分重新配置运行时中间件

//var runtimeMiddlewareService = serviceProvider.GetRequiredService<RuntimeMiddlewareService>();
//Or resolved via constructor.
runtimeMiddlewareService.Configure(runtimeApp =>
{
    //runtimeApp.Use...
    //Configurations here would override the former ones.
});