Yii2 CRUD:如何实现取消按钮

<?= Html::a('取消', ['index'], ['class' => 'btn btn-default']) ?>

public function actionCreate()
{
    // 处理表单提交逻辑

    if ($model->load(Yii::$app->request->post()) && $model->save()) {
        return $this->redirect(['index']);
    }

    return $this->render('create', [
        'model' => $model,
    ]);
}

return [
    // 其他路由规则

    'site/index' => 'site/index',
    'site/create' => 'site/create',
    'site/update' => 'site/update',
    'site/delete' => 'site/delete',
    'site/cancel' => 'site/index', // 取消按钮的路由规则
];