How to compile Android Native JAR libs
First of all we need to unzip the project.
Project archive can be found at:
You can copy this zip file to any comfortable place for your eclipse project and unzip in there.
You will find two folders in the zip archive. AndroidNativeEclipce project and facebook project for Unity Official SDK
Now we need to import those projects to ADT. Run the android ADT (Eclipse) you can get it from Android SDK download page.
After ADT is launched right click on Package Explorer tab and choose Import menu item.
In the import, setting choose Android → Existing Android Code Into Workspace
Hit next and press browse button.
Browse to the AndroidNativeEclipce project location and choose AndroidNativeEclipce folder and press Open.
Then just press Finish button.
You will see AndroidNative project imported to the ADT. It will have compilation errors because if we will open the Project Setting tab we will see that it dependent from facebook project. To get rid of that error, we should import facebook project in the same way we did with AndroidNativeEclipce project.
There may me more additional projects, like AN_Billing, AN_GooglePlay, AN_GooglePlay, etc.
As soon as we will do those, errors will gone, with means we can recompile androidnative.jar.
When you will change any script in the project jar file will be recompiled automatically, and you be able to find it under the project bin folder.
That it, now you can add your stuff and replace androidnative.jar in the Unity. the same approach for another jar libraries as well.