Android Studio之NDK开发（二）

深碍√TFBOYSˉ_ 2022-06-02 09:13 185阅读 0赞

接[上一篇NDK开发系列（一）][NDK]，继续介绍有关NDK开发技能

### 一，C++和CMake.txt里面都写了什么？ ###

##### native-lib.cpp中代码介绍： #####

![这里写图片描述][SouthEast]

##### app/CMakeLists.txt构建脚本翻译： #####

内容太多，不想看的童鞋点这里：[Android CMake.txt][]

# For more information about using CMake with Android Studio, read the
    # documentation: https://d.android.com/studio/projects/add-native-code.html
    
    # Sets the minimum version of CMake required to build the native library.
    #指定CMake编译器的最低版本3.4.1
    cmake_minimum_required(VERSION 3.4.1)
    
    #设置生成的so动态库最后输出的路径
    #它将会把生成的so库按照你在 build.gradle 指定的 abi分别放置在 jniLibs下
    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/./src/main/jniLibs/${ANDROID_ABI})
    
    # Creates and names a library, sets it as either STATIC
    # or SHARED, and provides the relative paths to its source code.
    # You can define multiple libraries, and CMake builds them for you.
    # Gradle automatically packages shared libraries with your APK.
    #翻译:创建一个类库的name,设置这个类库为STATIC
    #或者SHARED类型，并且设置c或者c++的源代码的的相对路径。
    #你可以定义多个类库，同事CMake会为你构建。
    #Gradle可以自动将shared类库打包到你的APK中。
    
    # CMake根据指定的源文件生成库文件
    add_library( # Sets the name of the library. #设置类库的名字
                 native-lib
    
                 # Sets the library as a shared library.
                  #生成的库的类型[SHARED|STATIC|MODULE]
                  #SHARED库会被动态链接，在运行时被加载
                  #STATIC库是在链接其它目标的时候使用
                 SHARED
    
                 # Provides a relative path to your source file(s).
                   #指定路径下的源文件代码，可以为这个类库指定多个.cpp文件
                 src/main/cpp/native-lib.cpp )
    
    # Searches for a specified prebuilt library and stores the path as a
    # variable. Because CMake includes system libraries in the search path by
    # default, you only need to specify the name of the public NDK library
    # you want to add. CMake verifies that the library exists before
    # completing its build.
    #翻译:搜索指定构建库并将变量作为存储路径。
    #因为Cmake构建工具默认包含了系统类库，你仅仅需要指定你想要添加的公共NDK类库的name.
    #CMake构建工具会在完成构建之前校验指定的类库name是否存在
    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 )
    
    # Specifies libraries CMake should link to your target library. You
    # can link multiple libraries, such as libraries you define in this
    # build script, prebuilt third-party libraries, or system libraries.
    #翻译:指定类库 CMake构建工具会连接到你的目标类库中。
    #你可以连接到多个类库中，例如：在这个CmakeLists.txt的构建脚本中定义的类库，
    #预构建的第三方类库或者系统类库。
    
    #为生成的目标类库指定需要的库文件
    target_link_libraries( # Specifies the target library.
                           #生成的目标库文件
                           native-lib
    
                           # Links the target library to the log library
                           # included in the NDK.
                           #需要在目标库文件中使用的库，表示可以在native-lib中使用log-lib库的内容
                           ${log-lib} )

#### 如何查找.so ####

*  方法一：app\\build\\intermediates\\jniLibs\\debug

![这里写图片描述][SouthEast 1]

*  方法二：通过CMake.txt指定路径

set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/./src/main/jniLibs/${ANDROID_ABI})

![这里写图片描述][SouthEast 2]

部分注意事项可以参考：[https://www.cnblogs.com/android-blogs/p/5867337.html][https_www.cnblogs.com_android-blogs_p_5867337.html]

[NDK]: http://blog.csdn.net/iblade/article/details/79013581
[SouthEast]: /images/20220602/6f3b463888524f5ebc8ab018c463d4fd.png
[Android CMake.txt]: http://blog.csdn.net/iblade/article/details/79077518
[SouthEast 1]: /images/20220602/2cdcb3c652a3435ea55db91cb5251e56.png
[SouthEast 2]: /images/20220602/8c832b3b1da4497782036f8ced75389f.png
[https_www.cnblogs.com_android-blogs_p_5867337.html]: https://www.cnblogs.com/android-blogs/p/5867337.html