在控制器的beforeAction方法中：

//eg: frontend\controllers\ArticleController中:
class ArticleController extends Controller
{
    public function beforeAction($action)
    {
        echo $action->controller->module->id;  //app-frontend
        echo $action->controller->id;          //article
        echo $action->id;                      //index
    }
}

在控制器中：

//eg: frontend\controllers\ArticleController中:
class ArticleController extends Controller
{
    public function actionIndex()
    {
        echo $this->module->id;  //app-frontend
        echo $this->id;          //article
        echo $this->action->id;  //index
    }
}

在视图（frontend\controllers\ArticleController的index方法对应的视图）中：

echo $this->context->module->id;  //app-frontend
echo $this->context->id;          //article
echo $this->context->action->id;  //index

还有一种在以上三种情况下都通用的方法：

echo Yii::$app->controller->module->id;  //app-frontend
echo Yii::$app->controller->id;          //article
echo Yii::$app->controller->action->id;  //index