安卓开发(二)：Native C++

• 向您的项目添加 C 和 C++ 代码:
  https://developer.android.google.cn/studio/projects/add-native-code?hl=zh-cn

com.example.myapplication.MainActivity.java

/**
 * A native method that is implemented by the 'myapplication' native library,
 * which is packaged with this application.
 */
public native String stringFromJNI();

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

extern "C" JNIEXPORT jstring JNICALL
Java_com_example_myapplication_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

Android基于NDK将C/C++代码编译生成库，供上层的Java/Cotlin应用调用
官方文档：https://developer.android.com/ndk?hl=zh-cn

• 通过直接调用 CMake 将 CMake 与 NDK 搭配使用
  https://developer.android.com/ndk/guides/cmake?hl=zh-cn#command-line

• 【Cmake】利用NDK进行Android的交叉编译（附实例）
  https://blog.csdn.net/qq_38410730/article/details/103622813

注意CMake编译时的各种参数

• ANDROID_ABI
  https://developer.android.com/ndk/guides/abis?hl=zh-cn
• ANDROID_PLATFORM
  https://developer.android.com/ndk/guides/cmake?hl=zh-cn#android_platform

何为交叉编译 (cross compile)
https://www.jianshu.com/p/bebab7c12991#1678095848039

CMake编译时需要指定NDK路径，指定工具链
build_for_android.sh脚本文件

Todo: JNI (Jave Native Interface)
cpp <---> jni <---> java