Katechaki (former reportengine.sourceforge.net) is a lightweight java API for reports. The reports can contain paragraphs, tables (with groupings, sorting, and totals/subtotals), pivot tables and other user defined components. Katechaki accepts input from memory, files and databases and exports the data in a multitude of formats: HTML, Excel, PDF, PNG, SVG etc.
Well, the former reportengine.sourceforge.net has been revived while I was staying in Athens – Katechaki avenue
Java 6 or higher