androidstudio cmake指定so文件輸出目錄

使用cmake來編譯jni代碼，找不到so文件在哪裏。雖然打包的時候會把so文件打包進去。
下面來配置CMakeLists.txt文件指定jniLibs爲so文件輸出目錄。

# 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)

# 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.
#設置生成的so動態庫最後輸出的路徑
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/../app/src/main/jniLibs/${ANDROID_ABI})
add_library( # Sets the name of the library.
             hello

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/jni/hello.c )

# 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.
                       hello

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )
由這個決定輸出目錄：
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/../app/src/main/jniLibs/${ANDROID_ABI})
它將會把生成的so庫按照你在 build.gradle 指定的 abi分別放置在 jniLibs下 
defaultConfig {
        applicationId "com.example.administrator.myapplication"
        minSdkVersion 15
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
        ndk {
            // Specifies the ABI configurations of your native
            // libraries Gradle should build and package with your APK.
            abiFilters 'armeabi'
        }