Opensource Candidate:
- Jasper Report (http://community.jaspersoft.com/project/jasperreports-library/resources)
- Dynamic Report (http://www.dynamicreports.org/)
- Dynamic Jasper (http://dynamicjasper.com/)
Comparison Part 1
http://lagivan.blogspot.hk/2011/10/choosing-java-reporting-tool.html
Comparison Part 2
http://lagivan.blogspot.hk/2011/11/choosing-java-reporting-tool-part-2.html