安卓编译环境设置

android {
    compileSdkVersion 23
    buildToolsVersion "27.0.2"

    defaultConfig {
        applicationId "com.ucool.heroesarena"
        minSdkVersion 16
        targetSdkVersion 19

        ndk {
            moduleName "hcu3dplugin"
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
    externalNativeBuild {
        ndkBuild {
            path '../../MOBA_ANDROID/AndroidBuild/HeroesArena/jni/Android.mk'
        }
    }
    splits {
        abi {
            // Configures multiple APKs based on screen density.
            enable true
            reset()  // Clears the default list from all densities to no densities.
            include "armeabi-v7a", "x86" // Specifies the two ABIs we want to generate APKs for.
        }
    }
}

NDK相关的编译

官方文档：Standalone Toolchains

Cross Compiling C/C++ for Android

生成tool-chain环境（由于android编译的target是丰富各异的安卓硬件平台，所以ndk的编译也需要根据平台来生成编译环境，所以提供了一个命令，如下是生成arm64平台的）：

./android-ndk-r12b/build/tools/make_standalone_toolchain.py --arch arm64 --install-dir ~/arm

编译的时候，可以使用如下命令：

~/arm/bin/clang -pie hello_world.c

查看编译文件的信息：

file a.out

在手机平台上运行：

adb push a.out /data/local/tmp/.
adb shell "./data/local/tmp/a.out"

#include 
int main () {
  puts("hello world");
}

一个简单的NDK的例子

TestCurl.cpp

#include 
extern "C" {
    JNIEXPORT jstring JNICALL
    Java_com_ucool_hellondk_MyNDK_stringFromJNI( JNIEnv* env,
                                                 jobject thiz ) {
        return (*env)->NewStringUTF(env, "Hello from JNI ! ");
    }
}

MyNDK.java

package com.ucool.hellondk;

public class MyNDK {
    static {
        System.loadLibrary("hello-jni");
    }
    public static native String  stringFromJNI();
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)

add_library(hello-jni SHARED
            TestCurl.cpp)

# Include libraries needed for hello-jni lib
target_link_libraries(hello-jni
                      android
                      log)

模块的build.gradle

android {
    compileSdkVersion 26
    // .....    
    externalNativeBuild {
        cmake {
            path 'src/main/jni/CMakeLists.txt'
        }

//        ndkBuild {
//            path 'src/main/jni/Android.mk'
//        }
    }
}

安卓的ToolChain环境的准备

# Create an arm64 API 26 libc++ toolchain.
$NDK/build/tools/make_standalone_toolchain.py --arch arm64  --stl=libc++   --install-dir=my-toolchain --force

or
%NDK%/build/tools/make-standalone-toolchain.sh --arch=arm64  --stl=libc++ --install-dir=my-toolchain  --force


# Add the standalone toolchain to the search path.
export PATH=$PATH:`pwd`/my-toolchain/bin

# Tell configure what tools to use.
target_host=aarch64-linux-android
export AR=$target_host-ar
export AS=$target_host-clang
export CC=$target_host-clang
export CXX=$target_host-clang++
export LD=$target_host-ld
export STRIP=$target_host-strip

# Tell configure what flags Android requires.
export CFLAGS="-fPIE -fPIC"
export LDFLAGS="-pie"


---------------------------------------------------

$ ./configure --host=arm
$ ./configure --host=arm --build=arm --with-sysroot=$ANDROID_SYSROOT

CMake的一个例子：

cmake_minimum_required(VERSION 3.4.1)

# 设置编译参数
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DUSE_FILE32API")

# 设置变量
set(BROTLI_DIR          "${CMAKE_CURRENT_SOURCE_DIR}/third_party/Brotli")
set(LIB_CURL_DIR        "${CMAKE_CURRENT_SOURCE_DIR}/prebuilt/libcurl")
set(H_CURL_DIR      "${LIB_CURL_DIR}/include")

# 头文件相关
include_directories("." ${H_CURL_DIR} )

# 编译源文件成Library
add_library(hcu3dplugin SHARED
            HcU3dPlugin.cpp
            JniHelper.cpp
            main.cpp
         )

# 编译子文件夹
add_subdirectory(${BROTLI_DIR} )

# 添加一个编译好的library
add_library(curl    STATIC IMPORTED )
set_target_properties(curl
                        PROPERTIES IMPORTED_LOCATION
                        ${LIB_CURL_DIR}/libs/${ANDROID_ABI}/libcurl.a )

# 连接其他文件
target_link_libraries(hcu3dplugin
                      brotli
                      curl
                     
                      android
                      log
                      z
                      )

CMake参考:

https://www.jetbrains.com/help/clion/quick-cmake-tutorial.html