Does anybody know how to get *.xlsx data into processing?

I've been searching without results for a possibility to read Excel's *.xlsx files using processing. There is however a library capable of reading *.xls. As expected, this library fails on reading *.xlsx.

I had a look at the content of the unpacked *.xlsx, especially at the xml files. However, the data seems not to bee easy accessible, data is spread across a sharedStrings.xml and the sheet#.xml files.

Any hint is appreciated! Thanks already! Also, any hint on commandline conversion of xlsx to xls or csv would be a great help!

Regards