Laravel 5.5 无法下载文件

php-7.2, laravel-5.5

请求下载方法，也没有报错，就是无法下载文件，提供代码，麻烦给我帮我瞅瞅。

public function getDownload(Request $request)
    {
        if ($request->filled('filename')) {
            $filename = $request->input('filename');
        } else {
            $this->ajaxError(1, '文件不存在');
        }

        $header = [
            "Cache-Control" => "max-age=0",
            "Content-Description" => "File Transfer",
            'Content-disposition' =>  'attachment; filename=' . basename($filename),
            "Content-Type" => "application/zip",
            "Content-Transfer-Encoding" => "binary",
            'Content-Length' =>  filesize($filename)
        ];
        return response()->download($filename, basename($filename), $header);
    }

响应头部

Accept-Ranges: bytes
Cache-Control: max-age=0, public
Connection: keep-alive
Content-Description: File Transfer
Content-Disposition: attachment; filename="100_2018-10-16-17-10.zip"
Content-Length: 162402
Content-Transfer-Encoding: binary
Content-Type: application/zip
Date: Tue, 16 Oct 2018 09:13:34 GMT
Last-Modified: Tue, 16 Oct 2018 09:10:36 GMT
Server: nginx/1.11.5
X-Powered-By: PHP/7.2.1