在laravel框架中接受inputs上传的文件一直报错，详细代码如下：

use Illuminate\Http\Request;
public function file(){
         $file = Request::file('photo');
         $allowed_extensions = ["png", "jpg", "gif"];
         if ($file->getClientOriginalExtension() && !in_array($file->getClientOriginalExtension(), $allowed_extensions)) {
             return ['error' => 'You may only upload png, jpg or gif.'];
         }
 
    }

报错如下：
1、Request使用错误：
Non-static method IlluminateHttpRequest::file() should not be called statically, assuming $this from incompatible context
2、getClientOriginalExtension()使用错误
Call to a member function getClientOriginalExtension() on string

希望大神指教，急急急！！！