controllerMap应该是‘\’吧

[wenhainan]

'controllerMap' => [
'file' => 'mdm\upload\FileController', // use to show or download file
],

[mdmunir]

?

[wenhainan]

i can't understand use what ?like.......
use yii\helpers\Html;
use yii\helpers\Url;
use yii\bootstrap\ActiveForm;
use frontend\assets\AppAsset;
use kartik\file\FileInput;
use yii\web\UploadedFile;
use mdm\upload\File; right here?