$transaction_excel_fp = fopen($transaction_excel_path, 'w');
fwrite($transaction_excel_fp,chr(0xEF).chr(0xBB).chr(0xBF));
fputcsv($cashback_excel_fp, [
    'aaa',
    'bbb',
]);
fclose($cashback_excel_fp);

//顺带一个知识点 csv处理成纯文本显示

protected function convertNumberToStringForExcel($value)
{
    return '=("' . $value . '")';
}