The libgdx project is a cross-platform game development library written in Java and using native code for performance. It abstracts away the differences between writing desktop and Android games based on OpenGL. Applications can be prototyped and developed entirely on the desktop, requiring few changes to run an app on Android.
The source for libgdx is available under the Apache 2.0 license.
The authors of the project also provide an assortment of tools, such as a texture packer and bitmap font exporter, for use with the library.