Is there a Java library (free and open source) that converts .dwg files directly to PDFs or images file? The .dwg uses recent normes of CAD (R14, R13, R12, and 2013).
I know that there are a few in .NET and C++... The ones in Java are mostly proprietary and expensive (example: Teigha for Java).
The free ones in Java such as Kabeja passes through an intermediary format, .dxf, which is a very huge file...
My take as of 2015:
After endless research and tests, I have concluded that there is currently NO FREE SOLUTION to convert AutoCAD .dwg files to PDF/image in Java which we can consider as reliable. This applies especially to latest versions of AutoCAD, for example: AutoCAD 2010, AutoCAD 2013, etc....
Reliable (and expensive) solutions would be Teigha by ODA (2000$ a year) and RealDWG in C# by AutoCAD (5000$ a year)...
Cheaper alternatives are as such:
Open-source libraries such as Kabeja and YCad may be able to deal with older AutoCAD versions, but do not expect much from them as these projects are inactive since a few years ago. It's worth to keep an eye out for Apache Tika though, since they started writing parsers for .dwg files, but development has been slow...