NDK--CMakeLists配置第三方so库

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

int sum(int a, int b) {
    return a + b;
}

#设置so库路径
set(my_lib_path ${CMAKE_SOURCE_DIR}/../../../libs)

#将第三方库作为动态库引用
add_library(test-lib
        SHARED
        IMPORTED)

#指定第三方库的绝对路径
set_target_properties(test-lib
        PROPERTIES IMPORTED_LOCATION
        ${my_lib_path}/${ANDROID_ABI}/libtest-lib.so)

target_link_libraries( # Specifies the target library.
        native-lib
        test-lib
        
        # Links the target library to the log library
        # included in the NDK.
        ${log-lib})

cmake_minimum_required(VERSION 3.4.1)

#设置so库路径
set(my_lib_path ${CMAKE_SOURCE_DIR}/libs)

#将第三方库作为动态库引用
add_library(test-lib
        SHARED
        IMPORTED)

#指定第三方库的绝对路径
set_target_properties(test-lib
        PROPERTIES IMPORTED_LOCATION
        ${my_lib_path}/${ANDROID_ABI}/libtest-lib.so)

add_library( # Sets the name of the library.
        native-lib

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        native-lib.cpp)

find_library( # Sets the name of the path variable.
        log-lib

        # Specifies the name of the NDK library that
        # you want CMake to locate.
        log)

target_link_libraries( # Specifies the target library.
        native-lib
        test-lib
        
        # Links the target library to the log library
        # included in the NDK.
        ${log-lib})

//
// Created by aruba on 2020/4/13.
//
#ifndef NDKAPPLICATION_TEST_LIB_H
#define NDKAPPLICATION_TEST_LIB_H

//申明外部 函数 外部属性
extern int sum(int a, int b);

#endif //NDKAPPLICATION_TEST_LIB_H

#include <jni.h>
#include <string>
#include <android/log.h>
#include <assert.h>
#include "test-lib.h"

#define TAG "C++"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))

extern "C"
JNIEXPORT jstring JNICALL native_stringFromJNI(JNIEnv *env, jclass type) {

    return env->NewStringUTF("C++");
}

JNIEXPORT jint JNICALL native_sum(JNIEnv *env, jclass type, jint a, jint b) {

    return sum(a, b);
}

static const JNINativeMethod gMethods[] = {
        {
                "stringFromJNI", "()Ljava/lang/String;", (void *) native_stringFromJNI
        },
        {
                "sum", "(II)I", (void *) native_sum
        }
};

static int registerNatives(JNIEnv *env) {
    LOGI("registerNatives begin");
    jclass clazz;
    //找到java的类
    clazz = env->FindClass("com/aruba/ndkapplication/JniUtils");

    if (clazz == NULL) {
        LOGI("clazz is null");
        return JNI_FALSE;
    }

    if (env->RegisterNatives(clazz, gMethods, NELEM(gMethods)) < 0) {
        LOGI("RegisterNatives error");
        return JNI_FALSE;
    }

    return JNI_TRUE;
}

JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
    LOGI("jni_OnLoad begin");

    JNIEnv *env = NULL;

    if (vm->GetEnv((void **) &env, JNI_VERSION_1_4) != JNI_OK) {
        LOGI("ERROR: GetEnv failed\n");
        return -1;
    }

    assert(env != NULL);

    registerNatives(env);

    return JNI_VERSION_1_4;
}

package com.aruba.ndkapplication;

public class JniUtils {
    static {
        System.loadLibrary("native-lib");
    }
    
    public static native String stringFromJNI();

    public static native int sum(int a, int b);
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Example of a call to a native method
        TextView tv = findViewById(R.id.sample_text);
        tv.setText(JniUtils.sum(10, 20) + "");
    }

}