vaadin viewchangelistener更改newView

Question

I try to change the newView of a navigation if the user is not authenticated and the newView is an instance of SecuredView . My approach was to check inside the beforeViewChange method if the constraints are given.

public boolean beforeViewChange(ViewChangeEvent event) {
    if (event.getNewView().getClass().isInstance(SecuredView.class) && VaadinService.getCurrentRequest().getUserPrincipal() == null) {
        event.getNavigator().navigateTo("login");
        return false;
    }
        return true;
    }
}

But that will result in a endless loop of redirection... How can i change the newView and stop the current navigation event?

Answer 1

1) If your View is not 'a correct view' it will end up in an endless loop. Try this simple view:

public class SecuredView extends VerticalLayout implements View {

    public SecureView() {
        addComponent(new Label("Secured View"));
    }

    @Override
    public void enter(ViewChangeEvent event) {
    }

}

2) Your if statement needs to be changed:

instead of:

event.getNewView().getClass().isInstance(SecuredView.class)

write:

SecuredView.class.isInstance(event.getNewView());