Android Studio CMake依赖第三方库

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这里实现一个简单的功能在APP里调用libnative-lib.so里的add。libnative-lib.so去调用libthird.so里的third_add来实现

JniUtil

public class JniUtil {
static {
System.loadLibrary("native-lib");
System.loadLibrary("third");
} public static native int add(int x,int y);
}

libnative.cpp

#include <jni.h>
#include <string>
#include "third.h"extern "C"{
JNIEXPORT jint JNICALL
Java_com_test_ndkthirdso_JniUtil_add(JNIEnv *env, jclass type, jint x, jint y) { // TODO
return third_add(x,y);
}JNIEXPORT jstring JNICALL
Java_com_test_ndkthirdso_MainActivity_stringFromJNI(
JNIEnv *env,
jobject /* this */) {
std::string hello = "Hello from C++";
return env->NewStringUTF(hello.c_str());
}}

这里编译好一个自己写一个libthird.so库实现一个加法功能

third.h

#ifndef __H_THIRD
#define __H_THIRD#ifdef __cplusplus
extern "C" {
#endifint third_add(int a, int b);#ifdef __cplusplus
}
#endif#endif // __H_THIRD

third.cpp

#include <jni.h>
#include "third.h"int third_add(int a, int b){
return a+b;
};

生成如下

项目工程结构如下：

CMakeLists.txt

cmake_minimum_required(VERSION 3.4.)
add_library(native-lib
SHARED
src/main/cpp/native-lib.cpp )find_library(log-lib
log )
#动态方式加载 third是libxxxx.so的xxxx部分
add_library(third SHARED IMPORTED)SET(third_path ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libthird.so)#设置要连接的so的相对路径，${ANDROID_ABI}表示so文件的ABI类型的路径,这一步引入了动态加入编译的so
set_target_properties(third PROPERTIES IMPORTED_LOCATION ${third_path})MESSAGE(STATUS “src third so path= ${third_path}”)#配置加载native依赖
include_directories( ${ProjectRoot}/app/src/main/cpp/external/include )target_link_libraries(native-lib third ${log-lib} )

gradle

apply plugin: 'com.android.application'android {
compileSdkVersion 26
buildToolsVersion "26.0.0"
defaultConfig {
applicationId "com.test.ndkthirdso"
minSdkVersion 15
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
externalNativeBuild {
cmake {
cppFlags "-frtti -fexceptions"
}
}
ndk {
// Specifies the ABI configurations of your native
// libraries Gradle should build and package with your APK.
abiFilters 'armeabi', 'armeabi-v7a'
}
} buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
externalNativeBuild {
cmake {
path "CMakeLists.txt"
}
}
}dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:26.+'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
}