public function actionIndex()
    {
        $extensions = Extension::find()->all();
        if (empty($extensions)) {
            echo "<empty list>";
        }
        echo"|";
        echo sprintf("%28s", "Class Name");
        echo"|";
        echo sprintf("%4s", "Enb");
        echo"|";
        echo sprintf("%4s", "Mnp");
        echo"|";
        echo sprintf("%4s", "Dft");
        echo"|";
        echo sprintf("%20s", "Create Time");
        echo"|";
        echo sprintf("%20s", "Update Time");
        echo"|";
        echo "\r\n";
        foreach ($extensions as $extension) {
            echo"|";
            echo sprintf("%28s", $extension->classname);
            echo"|";
            echo sprintf("%4d", $extension->isEnabled);
            echo"|";
            echo sprintf("%4d", $extension->monopolized);
            echo"|";
            echo sprintf("%4d", $extension->default);
            echo"|";
            echo sprintf("%20s", $extension->createdAt);
            echo"|";
            echo sprintf("%20s", $extension->updatedAt);
            echo"|";
            echo "\r\n";
        }
        return 0;
    }