CMake : 递归的添加所有cpp文件

最近在使用android studio的时候又发现了一个非常不方便的地方：

每次创建新的C++文件，都需要手动把新创建的C++文件名添加到CMakeLists.txt文件中，不然的话编辑器的顶部就会一直报：

目前我的项目结构如下：

 对应的CMakeLists.txt文件如下：

# 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.

cmake_minimum_required(VERSION 3.4.1)

# Add header file path
# include_directories(src/main/cpp/include)

# 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.

add_library( # Sets the name of the library.
        HaAlgorithm

        # Sets the library as a shared library.
        SHARED

        src/main/cpp/HaAptUserTuneJNI.cpp
        src/main/cpp/AndroidLog.cpp

        # Algorithm
        src/main/cpp/HaAlgorithm/apt_tune.cpp
        src/main/cpp/HaAlgorithm/invfreqz.cpp
        src/main/cpp/HaAlgorithm/main.cpp
        src/main/cpp/HaAlgorithm/sort_sos.cpp
        src/main/cpp/HaAlgorithm/tf2sos.cpp
        src/main/cpp/HaAlgorithm/user_tune_eq.cpp
        src/main/cpp/HaAlgorithm/wdrc_payload.cpp

        # CommandDefine
        src/main/cpp/HaCommandDefine/NoiseReductionPayload.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.

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.

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

可以看到，add_library 一行中已经添加了很多的cpp 文件， 有些还在第二级的子目录。

解决办法：

可以通过file指令搜索出所有后缀名为".cpp"的文件，然后添加到项目中，新的CMakeLists.txt修改如下：

cmake_minimum_required(VERSION 3.4.1)

set(CMAKE_CXX_STANDARD 11)

file(GLOB_RECURSE native_srcs src/main/cpp/*.cpp)

add_library(HaAlgorithm SHARED ${native_srcs})

target_link_libraries(
        HaAlgorithm
        android
        log
)

重点在于标红的那一句，什么意思呢，相当于告诉CMake, 搜索当前目录以及子目录中所有的以.cpp结尾的文件，然后把它们保存到  native_srcs 变量中。这里要注意CMakeLists.txt文件的位置，我是放在项目根目录下，所以我在搜索的时候指定了前缀：src/main/cpp。

这样修改之后，以后再添加新的C++代码就不需要再修改CMake文件了，编译APK的时候CMake会自动找出符合条件的C++文件并且参与到构建当中。

美中不足的是，虽然编译最终apk的时候,新添加的文件也会被编译，但是新添加的C++文件上方还是会出现：

 并且点击右边的“Sync Now” 之后还是没用！

经过反复尝试发现可以通过点击菜单栏上的“Refresh Linked  C++ Projects” 让它消失。