一、项目结构
-
项目配置
主要是里面cmake的配置，ndk配置，设置cMakeLists.txt
image.png - 目录结构
.cpp文件和它需要的.h文件都放在cpp文件夹下
.cpp文件依赖的.so文件则放在jniLibs文件夹下，jniLibs文件夹在Gradle脚本中是默认存放.so文件的位置，如果你想改它则需要在build.gradle中指定它的位置，如下设置:
sourceSets {
main {
jniLibs.srcDirs = ['libs']
}
}
build.gradle设置
apply plugin: 'com.android.application'
android {
compileSdkVersion 26
defaultConfig {
applicationId "com.example.dell.dualcampreview"
minSdkVersion 15
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
externalNativeBuild {
cmake {
cppFlags "-frtti -fexceptions"
}
}
ndk {
abiFilters 'armeabi-v7a'
}
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
externalNativeBuild {
cmake {
path "CMakeLists.txt"
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}
二、CMakeLists.txt中的设置
整体都是系统自动生成 的，只看关键的几个地方
- add_library()总共有三个
第一个是根据.cpp文件编译.so，如果有include的头文件的话，在后面加上include_directories()
第二个和第三个则是前面.cpp文件所需要的依赖的库文件，在后面需要加上set_target_properties()来它依赖的.so文件 - 末尾的 target_link_libraries，把前面的引入的库名都写上即可
# 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.
#此处可以通过多加几个addlibrary来针对多个cpp文件来生成多个.so文件
#它的用法跟Android.mk里的定义差不多
#需要留意，编译出来的文件放在\build\intermediates\cmake中,但是不用自己复制了，它会自动复制到
#jniLibs文件夹下
add_library(
jniSTDualCamPreview
SHARED
src/main/cpp/main.cpp
)
#include的文件夹
include_directories(jniSTDualCamPreview
${CMAKE_SOURCE_DIR}/src/main/cpp/include)
#两个预编译好的库
add_library(STdisp SHARED IMPORTED)
set_target_properties(STdisp PROPERTIES IMPORTED_LOCATION
${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libSTdisp.so)
add_library(Stereoblur SHARED IMPORTED)
set_target_properties(Stereoblur PROPERTIES IMPORTED_LOCATION
${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libStereoblur.so)
# 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.
jniSTDualCamPreview
STdisp
Stereoblur
# Links the target library to the log library
# included in the NDK.
${log-lib} )
三、遇到的一个异常情况
1.编译.cpp正常，但是build生成apk的时候出的异常
> More than one file was found with OS independent path 'lib/armeabi-v7a/libmainLib.so'
处理方式
其实是因为自己把编译.cpp生成的.so复制到了jniLibs下，但是cMakeList它其实会自己去编译和复制，并且自动放到jniLibs下，所以最后打包的时候就会报错More than one file
