Introduction: A gradle plugin that helps to output fat aar from android library
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This is a gradle plugin that helps to output fat aar from android library. I am inspired by android-fat-aar. And aim to make more flexible and functional. It's convenient to sdk developer(developer that provide a single aar library).

It works with the android gradle plugin, the android plugin's version of the development is 2.2.3, other revision is not tested actually. Commit an issue as you encounter some compatibility.

Update: Android plugin version 2.3.0 and later, is not well supported. disable build-cache may do the trick. So the recommend version is 2.2.3 and prior. Look this issue for more.

Essentially, fat-aar-plugin makes a hack way, to collect resources, jar files and something others in embedded dependencies, into the bundled output aar. Click here to know more about AAR.


  • Support embed android library project, java project, android library and java library from maven repositories. Local jar file is not needed to use embed, compile is enough.
  • Work fine with the original features provided by android plugin. Such as multi build type, product flavor, manifest placeholder, proguard... If you find something wrong, commit an issue.
  • The jar files in embedded dependencies will be bundled into libs\ in aar when the proguard is off. Otherwise , they will be bundled into classes.jar in aar, it means classes in dependencies will also be obfuscated.

Getting Started

Step 1: Apply plugin

Add snippet below to your root build script file:

buildscript {
    repositories {
        maven {
            url  "http://dl.bintray.com/vigidroid/maven"
    dependencies {
        classpath 'com.android.tools.build:gradle:xxx'
        classpath 'me.vigi:fat-aar-plugin:0.2.8'

Add snippet below to the build.gradle of your android library:

apply plugin: 'me.vigi.fat-aar'

Step 2: Embed dependencies

change compile to embed while you want to embed the dependency in the library. Like this:

dependencies {
    // aar project
    embed project(':aar-lib')
    // java project
    embed project(':java-lib')
    // java dependency
    embed 'com.google.guava:guava:20.0'
    // aar dependency
    embed 'com.android.volley:volley:1.0.0'

    // other dependencies you don't want to embed in
    compile 'com.squareup.okhttp3:okhttp:3.6.0'

More usage see example.

About AAR File

AAR is a file format for android library. The file itself is a zip file that containing useful stuff in android. See anatomy of an aar file here.

support list for now:

  • [x] manifest merge
  • [x] classes jar and external jars merge
  • [x] res merge
  • [x] R.txt merge
  • [x] assets merge
  • [x] jni libs merge
  • [x] proguard.txt merge
  • [ ] lint.jar merge
  • [ ] aidl merge?
  • [ ] public.txt merge?

Known Defects or Issues

  • Proguard note. Produce lots of(maybe) Note: duplicate definition of library class, while proguard is on. A workaround is to add -dontnote in proguard-rules.pro.
  • The overlay order of res merge is changed: Embedded dependency has higher priority than other dependencies.
  • Res merge conflicts. If the library res folder and embedded dependencies res have the same res Id(mostly string/app_name). A duplicate resources build exception will be thrown. To avoid res conflicts, consider using a prefix to each res Id, both in library res and aar dependencies if possible.
  • More issue or defect is welcomed...



About Me
GitHub: Trinea
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