Porting C++ Library to Android

References : http://kvurd.com/blog/compiling-a-cpp-library-for-android-with-android-studio/

Setup : Android Studio v1.4, NDK release 10, target SDK version of 14. Ubuntu (Linux-x86_64 was used).

Environment Variables : Download Android NDK in the given path NDK = /home/administrator/Android/Ndk ANDROID_CC=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-gcc ANDROID_CXX=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++

Overview : These are the steps:

Compile your library for Android a. libapayi.a Execute scons the apayi-cpp/android b. libcrypto.a (openssl) and libboost_system.a- Download android built libraries from online.
Create Android library project in Android Studio. a. Create android application project with no activity b. Replace apply plugin: 'com.android.application' with apply plugin: 'com.android.library' in app build.gradle c. Remove application id from android defaultConfig in app build.gradle d. Add in AndroidManifest.xml
Write the C/C++ wrapper for your library a. Create a prebuild\armeabi folder under project_root and copy your .a files and include files there. b. Create jni folder under project_root and create Android.mk and Application.mk file to mention the dependencies. Also include your .cpp file containing Java-jni calls .
Write Java wrapper classes
Run ndk-build
Configure gradle to package up your library a. Android Studio doesn't currently support NDK development so some gradle hacks are required. In a nutshell, the modifications copy and package up the .so file so that it is copied and installed with your app . b. In build.gradle add the following: task nativeLibsToJar(type: Zip, description: 'create a jar archive of the native libs') { destinationDir file("$buildDir/native-libs") baseName 'native-libs' extension 'jar' from fileTree(dir: 'libs', include: '**/*.so') into 'lib/' }
```
 tasks.withType(JavaCompile) {
     compileTask -> compileTask.dependsOn(nativeLibsToJar)
 } 
```
c. Also add the following to the dependencies{...} section: compile fileTree(dir: "$buildDir/native-libs", include: 'native-libs.jar')
Do a clean build to find The output is .aar (android archive) file which will be distributed as library to the users.
Test from java - Create sample app and include the aar to test the library.

prashant-agarwala/android_jni

Porting C++ Library to Android