Using Gradle with the Android plugin to add a JNI project to the APK.

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.3'
    }
}

sourceCompatibility = JavaVersion.VERSION_1_6
targetCompatibility = JavaVersion.VERSION_1_6

repositories {
    mavenCentral()
}

//apply plugin: 'java'
apply plugin: 'android'
android {
    compileSdkVersion 17
    defaultConfig {
        versionCode = 1
        versionName = "0.0"
    }
}


task wrapper(type: org.gradle.api.tasks.wrapper.Wrapper) {
    gradleVersion = '1.4'
}

dependencies{
  compile project(":subProject:jni")
}

settings.gradle

include ':subProject:jni'

subProject_jni_build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.3'
    }
}

sourceCompatibility = JavaVersion.VERSION_1_6
targetCompatibility = JavaVersion.VERSION_1_6

//apply plugin: 'java'
apply plugin: 'android-library'
//apply plugin: 'android'
android {
    compileSdkVersion 17
    defaultConfig {
        versionCode = 1
        versionName = "0.0"
    }
}

repositories {
    mavenCentral()
}

dependencies{
}

task wrapper(type: org.gradle.api.tasks.wrapper.Wrapper) {
    gradleVersion = '1.4'
}

task copyNativeLibs(type: Copy) {
  from fileTree(dir: 'libs', include: '**/*.so' )
	into  'build/native-libs'
}
 
tasks.withType(Compile) { compileTask -> compileTask.dependsOn copyNativeLibs }
 
clean.dependsOn 'cleanCopyNativeLibs'
	 
tasks.withType(com.android.build.gradle.tasks.PackageApplication) { pkgTask ->
	pkgTask.jniDir new File('build/native-libs')
}