Android NDK – Static & Shared Library Usage

Android NDK Version

android-ndk-r8b-windows.zip

Build Shared Library

Create file “Android.mk”under $PROJ_DIR/jni folder

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
include $(BUILD_SHARED_LIBRARY)

Build Static Library

Android NDK make will not build a static library by default. If you want to build a static library, you should introduce Application.mk (located in the same folder as Android.mk) or create a shared module that use the static library.

Method 1) Introduce the Application.mk

Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
include $(BUILD_STATIC_LIBRARY)

Application.mk

APP_MODULES := hello-jni

APP_PLATFORM := android-10 # Specify the android version, very important some times!

Method 2) Let the Static Library be used by Shared Library

Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE    := test
LOCAL_STATIC_LIBRARIES := hello-jni
include $(BUILD_SHARED_LIBRARY)

Build Static Library and Shared Library from source code

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := mylib_static
LOCAL_SRC_FILES := src.c
include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE    := mylib_shared
LOCAL_SRC_FILES := src2.c

LOCAL_STATIC_LIBRARIES := mylib_static

include $(BUILD_SHARED_LIBRARY)

Build Static/Shared Library into Shared/Static Library

Android.mk

LOCAL_PATH := $(call my-dir)

# static library introduced here
include $(CLEAR_VARS)
LOCAL_MODULE := thirdlib1      
LOCAL_SRC_FILES := $(TARGET_ARCH_ABI)/libthird1.a    #or $(so_path)/libthird1.so
#LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_STATIC_LIBRARY)    #or PREBUILT_SHARED_LIBRARY

# second library that use the previous library
include $(CLEAR_VARS)
LOCAL_MODULE    := mylib_use_thirdlib
LOCAL_SRC_FILES := src.c
LOCAL_STATIC_LIBRARIES := thirdlib1   #or LOCAL_SHARED_LIBRARY     
include $(BUILD_SHARED_LIBRARY)   #If need static one, refer how to build a static library