Holger Machens has created a Blender file import/export toolkit for Java. He also includes a good description of Blender's 'DNA' file format.
This is the documentation of the Java .Blend generic Blender file import/export toolkit for Java. Blender is an open source 3D graphic design and rendering environment which supports import and export of various file formats such as FBX and Collada. Imports and exports always require a mapping between different formats which inevitably involves compromises, resulting in loss of information. Java .Blend aims to fill the gap for Java programmers, who want type-safe access to all the data in a Blender file with read and write capabilities. To achive that, Java .Blend uses meta data which is contained in each Blender file, and describes Blender's entire core data model. This meta data is fed to Java .Blend's code generator, which generates Java classes for all types in Blender's data model and thereby creates a type-safe API to access raw data in a .blend file. Thus, there are no gaps in the model and every piece of a Blender file is available to the API programmer.