Can Android Studio be used to create Unity-plugin compatible JARs out of Library projects?

Question

When using Unity3d, "native" (pure-java) Android functionality can be accessed via Plugin. As described in the documentation,

There are several ways to create a Java plugin but the result in each case is that you end up with a .jar file containing the .class files for your plugin

When I create an Android Application Project in eclipse, and set it is a library, it automatically generates a .jar file in the bin folder. I understand that this is a temporary file in the context of the Android toolchain, but this is the file that Unity needs in order to see the classes and build up it's own internal JNI magic. (The entire process is outlined very well here in case more clarity is needed on that process.)

Unfortunately, as near as I can tell, Android Studio does not generate this file. Is there a way I can tell it to give me this file, or perhaps some other way to generate code that Unity will be able to use?

Answer 1

With Unity 5.3+ you no longer need to build a .jar, instead you can use the .aar file that is automatically created by an Android Studio Android Library module. I found this a lot easier than getting the jar method to work:

• In your Android Studio project, create an Android Library module: File > New > New Module > Android Library
• make sure your minSdkVersion and targetSdkVersion match your Unity project setup
• Add your classes etc to the module and build
• A successful build should create a .aar file in build/outputs/aar/ e.g. my module creates mkunityplugin-release.aar
• Open your Unity project, then drag the .aar file directly onto Assets/Plugins/Android in your Project view. This creates an asset which you can view in the inspector; it will show info on the plugin and the Android platform should be checked
• Build your Unity project for Android. My first attempt failed because I had a different targetSdkVersion so I got a build error saying the manifests could not be merged; I fixed that in my Android Studio build.gradle and then it worked

This is where I first heard that .aar could be used directly https://www.reddit.com/r/Unity3D/comments/3eltjz/how_to_add_an_android_library_project_folder_to/