Jxcell is a high performance java spreadsheet component that enables you to represent and display an Excel workbook in Java swing.
Jxcell contains the tools needed to store, analyze, manipulate, and present your data with excel spreadsheets.
Jxcell can be used as a rapid calculation engine embed in java server or client applications.
Jxcell can be used in Java desktop applications as an Excel-compatible,calculating grid with full support for spreadsheet formulas, functions, charts, data validations,and other spreadsheet features.

This version add more supports for Excel2007 OpenXML format.

http://www.jxcell.net