将byte []从xls转换为xlsx文件并保存

Question

I am trying to convert a byte[] I got from an XLS file I have elsewhere, into a new XLSX file and the save it. I'm using Free Spire.XML, but can't figure out how to do it.

public byte[] ConvierteAXLSX(string cuerpo)
{
    Workbook wb = new Workbook();
    Worksheet sheet = wb.Worksheets[0];
    byte[] array = Convert.FromBase64String(cuerpo);
    sheet.InsertArray(array, 1, 1, true);
    wb.SaveToFile(AppDomain.CurrentDomain.BaseDirectory +  "sample.xlsx", ExcelVersion.Version2013);
    byte[] fileContent = File.ReadAllBytes(AppDomain.CurrentDomain.BaseDirectory + "sample.xlsx");
    //File.Delete(AppDomain.CurrentDomain.BaseDirectory + "sample.xlsx");
    return fileContent;
}

This code creates the XLSX file, but just inserts the byte[] into the excel file like an array, instead of converting the data.

Edit:

My problem is slightly different from that other question. I can't just read the original file and then save it again, since the file is in another server and can't access it. The best thing I can do is send the document body and parse it into byte[].

It also works if I can convert my byte[] into a XLS file and save it, then I could use the answer to the other similar question.

Workbook workbook = new Workbook();
workbook.LoadFromFile("Input.xls");
workbook.SaveToFile("Output.xlsx", ExcelVersion.Version2013);

Answer 1

This is not going to war as the two file types store data completely different. The data in the xls file is stored in a proprietary binary format and the xmls file data is stored in Open XML.

Answer 2

I did it, saved the byte[] into a XLS file, read it and saved it again into a XLSX file.

public byte[] ConvierteAXLSX(string cuerpo)
        {
            File.WriteAllBytes(AppDomain.CurrentDomain.BaseDirectory + "viejo.xls", Convert.FromBase64String(cuerpo));
            Workbook workbook = new Workbook();
            workbook.LoadFromFile(AppDomain.CurrentDomain.BaseDirectory + "viejo.xls");
            workbook.SaveToFile(AppDomain.CurrentDomain.BaseDirectory + "nuevo.xlsx", ExcelVersion.Version2013);
            byte[] fileContent = File.ReadAllBytes(AppDomain.CurrentDomain.BaseDirectory + "nuevo.xlsx");
            File.Delete(AppDomain.CurrentDomain.BaseDirectory + "viejo.xls");
            File.Delete(AppDomain.CurrentDomain.BaseDirectory + "nuevo.xlsx");
            return fileContent;
        }

Thanks for your help!