Laravel Middleware没有采用特定的方法

I want to use middleware in Usercontroller on only getDashboard() and getUserlist() method, but it didn't work for me. also I add in controller constructor.

My Controller:

class Usercontroller extends Controller {

public function __construct() {
$this->middleware('auth',['only' => ['getDashboard']]);
//$this->middleware('auth');
}

##This method render home view.

public function index() {
    //  dd('yahoo');
    return view('welcome');
}
 ##To add new user.

public function getAdduser() {
    return view('register');
}

#To render dashboard view.

public function getDashboard() {
    return view('dashboard');
}

When I directly type in url http://localhost/rabble/index.php/user/dashboard.it still display display without authenticate user is login or not.