use Dancer;
use utf8;
use Excel::Writer::XLSX;         # Step 0

get '/xxx' => sub {
    my $buffer;
    open my $fh, '>', \$buffer;
    my $workbook = Excel::Writer::XLSX->new( $fh );    # Step 1
    my $worksheet = $workbook->add_worksheet();        # Step 2
    $worksheet->write( 'A1', 'Hi Excel!' );            # Step 3
    $workbook->close();
    close $fh;
    return send_file(
        \$buffer,
        content_type => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        filename     => 'xxx.xlsx',
    );
};

dance;