如何在另一个Android应用程序中调用Android ndk build .so文件？

Question

I have an requirement which i have to build .so file using NDK build in Android and I have to call some of the methods from the .so file in my other Android application.

What I have tried so far.

I have taken the .so file from the lib folder of my Android project and put in my other application libs folder where I should call that .so file. I have used the below code:

Note: I am using ECLIPSE

static {
        System.loadLibrary("NativeCode");
    }

and also tried with full path of library

static {
        System.loadLibrary("fullpath\NativeCode");
    }

both the cases its giving unsatisfiedLinkError that mean it's not getting the path of my .so file.

Answer 1

You need to have your libNativeCode.so in the jni folder of your root, and not in the libs or lib folder

Here is a nice tutorial : http://www3.ntu.edu.sg/home/ehchua/programming/android/android_ndk.html

Alternatively, you can use following commands:

    adb shell
    $echo $PATH

What it will do is display a path like this :

/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin

You can have your .so in any of these folders like /system , /system/bin , /system/sbin . (Remember, but you would need to manually copy it, and it is not a good idea to do so for an app)

Edit : You can not call any JNI function in your app, because the signature. You need to have a JNI wrapper (a .so JNI lib that in turn uses the .h header file to call the JNI function of the other library). This is because JNI is very sensitive to signatures. So, as I recommended earlier, follow the tutorial !

Answer 2

In order to get your .so library to be loaded using loadLibrary() you'll have to copy the libNativeCode.so lib into the jniLibs/architecture folder.

The folder should be located under src/main/jniLibs/armeabi-v7a of your Android Application module (assuming you're using Android Studio).

After you copy the libraries, add the following line to your build.gradle located at the app module folder:

assert file("./src/main/jniLibs/armeabi-v7a/libNativeCode.so").exists()

After you'll complete the above steps it should load the lib properly.

If the libNativeCode.so is located at the wrong path, the Gradle build will fail.

Good luck,