控制器不存在:app\index\controller\Download

        $this->app['hook']->listen('module_init');

        try {
            // 实例化控制器
            $instance = $this->app->controller($this->controller,
                $this->rule->getConfig('url_controller_layer'),
                $this->rule->getConfig('controller_suffix'),
                $this->rule->getConfig('empty_controller'));
        } catch (ClassNotFoundException $e) {
            throw new HttpException(404, 'controller not exists:' . $e->getClass());
        }

        $this->app['middleware']->controller(function (Request $request, $next) use ($instance) {
            // 获取当前操作名
            $action = $this->actionName . $this->rule->getConfig('action_suffix');

            if (is_callable([$instance, $action])) {
                // 执行操作方法
                $call = [$instance, $action];