如何从Android中的本机层文件中回调应用程序层文件？

Question

I have below three files in my Android project (one java file in Application layer, one cpp file in JNI layer & one cpp file in Native layer).

1. MyActivity.java (Application Layer)
2. MyJNIInterface.cpp (JNI Interface)
3. MyNativeFile.cpp. (Native implementation)

I am able to call a api in Native Layer from Application Layer using JNI interface.

Is there a way through which I can have a callback to the Application Layer file (MyActivity.java) from Native Layer file (MyNativeFile.cpp)?

Please share some sample code.

Answer 1

Yes, it is possible.

Check this sample app provided by Google

Answer 2

Android fully implements standard JNI (except JNI_CreateJavaVM() ), so callbacks are supported. Note that you must attach your thread to JVM if you want to call Java back from a thread that was not started in Java (eg UI thread does not need AttachCurrentThread() ).