    public function avatar($avatar_name)
    {
        list($user_id,$size) = explode('_',str_replace(".jpg",'',$avatar_name));
        $avatarFile = storage_path('app/'.User::getAvatarPath($user_id,$size));
        if(!is_file($avatarFile)){
            $avatarFile = public_path('static/images/default_avatar.jpg');
        }
        $image =   Image::make($avatarFile);
        $response = response()->make($image->encode('jpg'));
        $image->destroy();
        $response->header('Content-Type', 'image/jpeg');
        $response->header('Expires',  date(DATE_RFC822,strtotime(" 2 day")));
        $response->header('Cache-Control', 'private, max-age=86400, pre-check=86400');
        return $response;
    }