在ASP.NET 5中,如何在中间件中获取所选路由？

public static class TokenAuthenticationExtensions
{
    public static IApplicationBuilder UseTokenAuthentication(this IApplicationBuilder app,Action<IRouteBuilder> configureRoutes)
    {
        var routes = new RouteBuilder
        {
            DefaultHandler = new TokenRouteHandler(),ServiceProvider = app.ApplicationServices
        };

        configureRoutes(routes);

        routes.Routes.Insert(0,AttributeRouting.CreateAttributeMegaRoute(
            routes.DefaultHandler,app.ApplicationServices));

        return app.UseRouter(routes.Build());
    }
}

然后你创建自己的this class版本.在我的情况下,我实际上并不想调用这些动作.我会让典型的Mvc中间件做到这一点.因为在这种情况下,我将所有相关代码排除在外,并保留了我需要获取的路径数据,该数据位于actionDescriptor变量中.我可能可以删除处理备份路由数据的代码,因为我不认为我将要做的事情会影响数据,但我已将其保留在示例中.这是我将基于mvc路由处理程序开始的框架.

public class TokenRouteHandler : IRouter
{
    private IActionSelector _actionSelector;

    public VirtualPathData GetVirtualPath(VirtualPathContext context)
    {
        EnsureServices(context.Context);

        context.IsBound = _actionSelector.HasValidAction(context);

        return null;
    }

    public async Task RouteAsync(RouteContext context)
    {
        var services = context.HttpContext.RequestServices;

        EnsureServices(context.HttpContext);

        var actionDescriptor = await _actionSelector.SelectAsync(context);
        if (actionDescriptor == null)
        {
            return;
        }

        var oldRouteData = context.RouteData;
        var newRouteData = new RouteData(oldRouteData);

        if (actionDescriptor.RouteValueDefaults != null)
        {
            foreach (var kvp in actionDescriptor.RouteValueDefaults)
            {
                if (!newRouteData.Values.ContainsKey(kvp.Key))
                {
                    newRouteData.Values.Add(kvp.Key,kvp.Value);
                }
            }
        }

        try
        {
            context.RouteData = newRouteData;

            //Authentication code will go here  <-----------
            var authenticated = true;

            if (!authenticated)
            {
                context.IsHandled = true;
            }
        }
        finally
        {
            if (!context.IsHandled)
            {
                context.RouteData = oldRouteData;
            }
        }
    }

    private void EnsureServices(HttpContext context)
    {
        if (_actionSelector == null)
        {
            _actionSelector = context.RequestServices.GetRequiredService<IActionSelector>();
        }            
    }
}

最后,在管道末尾的Startup.cs文件的Configure方法中,我进行了设置,以便对我的令牌认证和mvc路由器使用相同的路由设置(我使用属性路由).

public void Configure(IApplicationBuilder app,IHostingEnvironment env,ILoggerFactory loggerFactory)
    {
        //Other middleware delcartions here <----------------

        Action<IRouteBuilder> routeBuilder = routes =>
        {
            routes.MapRoute(
                name: "default",template: "{controller=Home}/{action=Index}/{id?}");
        };

        app.UseTokenAuthentication(routeBuilder);

        //Middleware after this point will be blocked if authentication fails by having the TokenRouteHandler setting context.IsHandled to true

        app.UseMvc(routeBuilder);
    }

编辑1：
我还应该注意到,目前我并不关心两次选择路由所需的额外时间,这是我认为会发生的事情,因为我的中间件和Mvc中间件都会这样做.如果这成为性能问题,那么我将在一个处理程序中构建mvc和身份验证.这在性能方面是最好的想法,但我在这里展示的是我认为最模块化的方法.

编辑2：最后,为了得到我需要的信息,我必须将ActionDescriptor转换为ControllerActionDescriptor.我不确定您可以在ASP.NET中执行哪些其他类型的操作,但我非常确定我的所有操作描述符都应该是ControllerActionDescriptors.也许旧的遗留Web Api东西需要另一种类型的ActionDescriptor.