JDK is not included, but JDK 6 or JDK 5.0 is required for installing and running NetBeans IDE.

NetBeans source code and binary builds without bundled runtimes are also available in zip file format.
Instructions on how to build the IDE from sources are documented in NetBeans wiki.

NetBeans Platform is part of NetBeans IDE, if you need it separately, you can download it download the platform