Laravel8导出excel返回值的简单想法

最近在使用Maatwebsite\Excel扩展进行excel的导出功能，具体怎么操作，这里不详细说了，通过下面代码导出：

//导出excel【$head是excel表头，$list是数据】
return Excel::download(new CustomerExport($head, $list), date('YmdHis') . '.xls');

我本着好奇打印这个返回值：

print_r(Excel::download(new CustomerExport($head, $list), date('YmdHis') . '.xls'));

结果如下：

Symfony\Component\HttpFoundation\BinaryFileResponse Object
(
[file:protected] => Symfony\Component\HttpFoundation\File\File Object
(
[pathName:SplFileInfo:private] => /home/vagrant/www/admin/storage/framework/cache/laravel-excel/laravel-excel-4U89uL9YLn4vNb1QrCDelsmv4Yrk3Ff.xls
[fileName:SplFileInfo:private] => laravel-excel-4U89uL9YLn4vNb1QrCDelsmv4Yrk3Ff.xls
)
[offset:protected] => 0
[maxlen:protected] => -1
[deleteFileAfterSend:protected] => 1
[headers] => Symfony\Component\HttpFoundation\ResponseHeaderBag Object
(
[computedCacheControl:protected] => Array
(
[public] => 1
)
[COOKIEs:protected] => Array
(
)
[headerNames:protected] => Array
(
[cache-control] => Cache-Control
[date] => Date
[last-modified] => Last-Modified
[content-disposition] => Content-Disposition
)
[headers:protected] => Array
(
[cache-control] => Array
(
[0] => public
)
[date] => Array
(
[0] => Thu, 08 Dec 2022 05:57:26 GMT
)
[last-modified] => Array
(
[0] => Thu, 08 Dec 2022 07:16:21 GMT
)
[content-disposition] => Array
(
[0] => attachment; filename=20221208152026.xls
)
)
[cacheControl:protected] => Array
(
[public] => 1
)
)
[content:protected] =>
[version:protected] => 1.0
[statusCode:protected] => 200
[statusText:protected] => OK
[charset:protected] =>
)

很明显他是个对象。

因为我是前后端分离的，接口也是直接上面代码的，前端同学使用a标签跳到接口地址进行下载的，可以成功。但是打开F12的network查看返回值，前端拿到的是文件流，如下：

为什么直接运行接口返回的是个对象，前端拿到居然变为文件流了？

原来是返回的时候，自动给返回头加了两个参数

Content-Disposition:attachment; filename=20221208152026.xls
Content-Type:application/vnd.ms-excel

Content-Disposition不就是对象里面的头消息嘛