Android studio使用ndk-build进行编译

在studio2.3 中创建一个ndk工程，该工程默认是通过cmake进行编译，我们修改为使用熟悉的ndk-build来编译, 这样可以编写自己的makefile。

方法1: （Android.mk & Gradle）

1 在studio中创建jni目录 app/src/main/jni

app->右键->new->Folder->Jni Folder
选择 change folder location ， 对应src/main/jni

2 在jni目录编写Android.mk 和 Application.mk

3 编辑 app/build.gradle

android{
externalNativeBuild {
ndkBuild {
path'src/main/jni/Android.mk'
}
}
sourceSets { main { jni.srcDirs = ['src/main/jni', 'src/main/jni/'] } }
}

该方法Application.mk不再使用，需要把内容对应到 build.gradle:

defaultConfig {
externalNativeBuild {
ndkBuild {
...
abiFilters "armeabi-v7a", "armeabi"
}
}
}

更详细内容参考Google官方文档:

https://sites.google.com/a/android.com/tools/tech-docs/external-c-builds#TOC-Release-History

方法2 :（Android.mk & Application.mk）

1 手动创建jni目录 app/src/main/jni

2 在jni目录编写Android.mk 和 Application.mk

3 编辑 app/build.gradle.

1). 删除ndk section

ndk{}

2). 增加import org.apache.tools.ant.taskdefs.condition.Os

import org.apache.tools.ant.taskdefs.condition.Os

apply plugin: 'com.android.application'
android {
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
applicationId "com.packtpub.store"
minSdkVersion 14
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'),
'proguard-rules.pro'
}
}

3) 增加sourceSets.main section

sourceSets.main {
jniLibs.srcDir 'src/main/libs'
jni.srcDirs = []
}

jniLibs.srcDir, 定义gradle去什么的地方找产生的库文件
jni.srcDirs,    定义静止gradle编译 native code

4) 最后创建新的Gradle 任务 ndkbuild,定义src/main 为编译路径

task ndkBuild(type: Exec) {
if (Os.isFamily(Os.FAMILY_WINDOWS)) {
commandLine 'ndk-build.cmd', '-C', file('src/main').absolutePath
} else {
commandLine 'ndk-build', '-C', file('src/main').absolutePath
}
}
tasks.withType(JavaCompile) {
compileTask -> compileTask.dependsOn ndkBuild
}

修改后的build.gradle:

import org.apache.tools.ant.taskdefs.condition.Os

apply plugin: 'com.android.application'

android {
compileSdkVersion 26
buildToolsVersion "26.0.1"
defaultConfig {
applicationId "com.example.hello"
minSdkVersion 14
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile
('proguard-android.txt'), 'proguard-rules.pro'
}
}
sourceSets.main {
jniLibs.srcDir 'src/main/libs'
jni.srcDirs = []
}
task ndkBuild(type: Exec) {
if (Os.isFamily(Os.FAMILY_WINDOWS)) {
commandLine 'ndk-build.cmd', '-C', file('src/main').absolutePath
} else {
commandLine 'ndk-build', '-C', file('src/main').absolutePath
}
}
tasks.withType(JavaCompile) {
compileTask -> compileTask.dependsOn ndkBuild
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:
espresso-core:2.2.2', {
exclude group: 'com.android.support', module:
'support-annotations'
})
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
}