ndk项目收藏

帮助集成第三方jni代码。c、c++需要额外学习才能精通ndk开发。

第一个是文件加密解密，分割合并。

extern "C"
JNIEXPORT jboolean JNICALL
Java_cn_cfanr_ndksample_utils_FileUtils_fileEncrypt(JNIEnv *env, jclass type, jstring normalFilePath_,
                                                    jstring encryptFilePath_) {
    const char *normalFilePath = env->GetStringUTFChars(normalFilePath_, 0);
    const char *encryptFilePath = env->GetStringUTFChars(encryptFilePath_, 0);

    int passwordLen = strlen(PASSWORD);

    LOGE("要加密的文件的路径 = %s , 加密后的文件的路径 = %s", normalFilePath, encryptFilePath);

    //读文件指针
    FILE *frp = fopen(normalFilePath, "rb");
    // 写文件指针
    FILE *fwp = fopen(encryptFilePath, "wb");

    if (frp == NULL) {
        LOGE("文件不存在");
        return JNI_FALSE;
    }
    if (fwp == NULL) {
        LOGE("没有写权限");
        return JNI_FALSE;
    }

    // 边读边写边加密
    int buffer;
    int index = 0;
    while ((buffer = fgetc(frp)) != EOF) {
        // write
        fputc(buffer ^ *(PASSWORD + (index % passwordLen)), fwp);  //异或的方式加密
        index++;
    }
    // 关闭文件流
    fclose(fwp);
    fclose(frp);

    LOGE("文件加密成功");

    env->ReleaseStringUTFChars(normalFilePath_, normalFilePath);
    env->ReleaseStringUTFChars(encryptFilePath_, encryptFilePath);

    return JNI_TRUE;
}

直接通过c中的fputc函数，进行异或运算。
需要注意当我把图片压缩c代码放在与当前目录时，编译报错。因此新建module，独立CMakeLists工程编译两个项目。

第二个，图片质量压缩。
CMakeLists.txt

# Sets the minimum version of CMake required to build the native library.
cmake_minimum_required(VERSION 3.4.1)

#设置生成的so动态库最后输出的路径
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI})

#指定要引用的libjpeg.so的头文件目录
set(LIBJPEG_INCLUDE_DIR src/main/cpp/include)
include_directories(${LIBJPEG_INCLUDE_DIR})

#导入libjpeg动态库 SHARED；静态库为STATIC
add_library(jpeg SHARED IMPORTED)
#对应so目录，这里为了简单设置的是绝对路径（注意要先 add_library，再 set_target_properties）
set_target_properties(jpeg PROPERTIES IMPORTED_LOCATION ${PROJECT_SOURCE_DIR}/libs/${ANDROID_ABI}/libjpeg.so)

add_library(
             compress
             SHARED
             src/main/cpp/compress.c
             )

find_library(graphics jnigraphics)
find_library(log-lib log)

target_link_libraries(compress jpeg ${log-lib} ${graphics})

引入了graphics库，和libjpeg.so动态库。

JNIEXPORT jboolean JNICALL
Java_cn_cfanr_compress_ImageCompress_compressBitmap(JNIEnv *env, jclass type, jobject bitmap,
                                                    jstring dstPath_, jint quality,
                                                    jboolean isOptimize) {
    AndroidBitmapInfo androidBitmapInfo;
    BYTE *pixelsColor;
    int ret;
    BYTE *data;
    BYTE *tmpData;
    const char *dstFileName = jstringToString(env, dstPath_);
    //解码Android Bitmap信息
    if ((ret = AndroidBitmap_getInfo(env, bitmap, &androidBitmapInfo)) < 0) {
        LOGD("AndroidBitmap_getInfo() failed error=%d", ret);
        return false;
    }
    if ((ret = AndroidBitmap_lockPixels(env, bitmap, (void **)&pixelsColor)) < 0) {
        LOGD("AndroidBitmap_lockPixels() failed error=%d", ret);
        return false;
    }

    LOGD("bitmap: width=%d,height=%d,size=%d , format=%d ",
         androidBitmapInfo.width, androidBitmapInfo.height,
         androidBitmapInfo.height * androidBitmapInfo.width,
         androidBitmapInfo.format);

    BYTE r, g, b;
    int color;

    int w, h, format;
    w = androidBitmapInfo.width;
    h = androidBitmapInfo.height;
    format = androidBitmapInfo.format;

    data = (BYTE *) malloc(androidBitmapInfo.width * androidBitmapInfo.height * 3);
    tmpData = data;
    // 将bitmap转换为rgb数据
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            //只处理 RGBA_8888
            if (format == ANDROID_BITMAP_FORMAT_RGBA_8888) {
                color = (*(int *) (pixelsColor));
                // 这里取到的颜色对应的 A B G R  各占8位
                b = (color >> 16) & 0xFF;
                g = (color >> 8) & 0xFF;
                r = (color >> 0) & 0xFF;
                *data = r;
                *(data + 1) = g;
                *(data + 2) = b;

                data += 3;
                pixelsColor += 4;

            } else {
                return -2;
            }
        }
    }
    AndroidBitmap_unlockPixels(env, bitmap);
    //进行压缩
    ret = generateJPEG(tmpData, w, h, quality, dstFileName, isOptimize);
    free((void *) dstFileName);
    free((void *) tmpData);
    return true;
}

完整项目代码:https://github.com/androiddeveloper007/NdkProjectCollect