将依赖的.so文件与ndk-build for Android链接

Question

I have created a .so file that exposes a native C call to Java via JNI. This works well and I can deploy the app onto my Android system if I just use system libraries in my C code. However, if I want to make calls to functions in other .so files, I cannot get my project to link correctly.

For example, say I have the "libotherso.so" file which contains APIs defined in C that I can call from the "MyJNILibrary.c" code I'm using to generate "libMyJNILibrary.so".

I tried to change my Android.mk file as follows:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := MyJNILibrary
LOCAL_SRC_FILES := MyJNILibrary.c

LOCAL_LDLIBS += -lotherso

include $(BUILD_SHARED_LIBRARY) 

But when I call ndk-build on this, I get errors finding -lotherso. Where do I put the "libotherso.so" file so that ndk-build can pick it up?

Thanks for any help you can provide.

Answer 1

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := otherso
LOCAL_SRC_FILES := ../lib/libotherso.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE    := MyJNILibrary
LOCAL_SRC_FILES := MyJNILibrary.c
LOCAL_SHARED_LIBRARIES := otherso
include $(BUILD_SHARED_LIBRARY) 

Note that LOCAL_SRC_FILES is relative to your LOCAL_PATH.

Don't forget to load your dependency before your own JNI library:

static {
  System.loadLibrary("otherso");
  System.loadLibrary("MyJNILibrary");
}