phpoffice/phpspreadsheet 使用报错

public function importExcel(Request $request){
        $ufile = $request->file('excelName');

        if(isset($ufile)){
            $spreadsheet = \PhpOffice\PhpSpreadsheet\IOFactory::load($ufile->getRealPath());
        }
        return json($spreadsheet);
    }

"error":"Class \"PhpOffice\\PhpSpreadsheet\\IOFactory\" not found"