Android NDK 会加密编译的 c++ 文件吗？

Question

I have a C++ file on my Android project ( native-lib.cpp ):

#include <jni.h>
#include <string>

extern "C" JNIEXPORT jstring JNICALL
Java_com_example_keysnative_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string api_key = "0123456789abcdef";
    return env->NewStringUTF(api_key.c_str());
}

When I build the project and unpack the apk, this file will be compiled into a binary: lib/x86/libnative-lib.so .

If I then try importing and use this file into another project I get an error:

public class Main {

    static {
        try {
            System.load("/Users/u/Playground/KeysNative/app-debug/lib/x86/libnative-lib.so");
        } catch (UnsatisfiedLinkError e) {
            System.err.println(e);
            System.exit(1);
        }
    }
}

java.lang.UnsatisfiedLinkError: /Users/u/Playground/KeysNative/app-debug/lib/x86/libnative-lib.so: dlopen(/Users/u/Playground/KeysNative/app-debug/lib/x86/libnative-lib.so, 1): no suitable image found. Did find: /Users/u/Playground/KeysNative/app-debug/lib/x86/libnative-lib.so: unknown file type, first eight bytes: 0x7F 0x45 0x4C 0x46 0x01 0x01 0x01 0x00 /Users/u/Playground/KeysNative/app-debug/lib/x86/libnative-lib.so: unknown file type, first eight bytes: 0x7F 0x45 0x4C 0x46 0x01 0x01 0x01 0x00

Question: Do these files use the java keystore in the project to be compiled, or any other kind of signature?

Answer 1

You cannot load native assemble from your computers file-system on a mobile device.

This should already suffice to link the assembly:

static {
    try {
        System.loadLibrary("libnative-lib");
    } catch (UnsatisfiedLinkError e) {
        Log.e(LOG_TAG, "" + e.getMessage());
    }
}

However, if you only have x86 assembly, this will only work on a x86 Android emulator.

Answer 2

正如@Michael 所说，因为 .so 是从 Android NDK 生成的，它包含 Android 依赖项，因此只能在 Android 系统上运行。