How to read existing excel file with xlsio and flutter

Question

To create an excel file in xlsio (in Flutter) See docs the following code is needed:

// Create a new Excel document.
final Workbook workbook = new Workbook();

But how do I find an existing excel file (I am building a desktop app) in a given directory and work with that in xlsio?

Broteen Das · Answer

Apparently there is no easy way to read an existing excel file. So I just used the excel package to read the files. (Suggessted by @TripleNine)