将JNI模块打包为AAR模块

1，指定为aar模块：

apply plugin: 'com.android.library'

2，指定源码目录，将已经打包好的so文件放入libs目录下
sourceSets {
main {
manifest {
srcFile 'AndroidManifest.xml'
}
java {
srcDir 'src'
}
jniLibs {
srcDirs 'libs'//JNI的so文件位置，打入aar文件
}
}
}

3，如果是c源代码，将所有c代码放到jni目录，然后在build.gradle中添加如下编译代码：
//编译JNI文件夹C代码
task buildNative(type: Exec, description: 'Compile JNI source via NDK') {
def ndkDir = android.plugin.ndkFolder
if (org.apache.tools.ant.taskdefs.condition.Os.isFamily(org.apache.tools.ant.taskdefs.condition.Os.FAMILY_WINDOWS)) {
commandLine "$ndkDir/ndk-build.cmd",
'-C', file('jni').absolutePath, // Change src/main/jni the relative path to your jni source
'-j', Runtime.runtime.availableProcessors(),
'all',
'NDK_DEBUG=1'
} else {
commandLine "$ndkDir/ndk-build",
'-C', file('jni').absolutePath, // Change src/main/jni the relative path to your jni source
'-j', Runtime.runtime.availableProcessors(),
'all',
'NDK_DEBUG=1'
}
}

task cleanNative(type: Exec, description: 'Clean JNI object files') {
def ndkDir = android.plugin.ndkFolder
if (org.apache.tools.ant.taskdefs.condition.Os.isFamily(org.apache.tools.ant.taskdefs.condition.Os.FAMILY_WINDOWS)) {
commandLine "$ndkDir/ndk-build.cmd",
'-C', file('jni').absolutePath, // Change src/main/jni the relative path to your jni source
'clean'
} else {
commandLine "$ndkDir/ndk-build",
'-C', file('jni').absolutePath, // Change src/main/jni the relative path to your jni source
'clean'
}
}

clean.dependsOn 'cleanNative'

tasks.withType(JavaCompile) {
compileTask -> compileTask.dependsOn buildNative
}


4，./gradlew build   直接编译即可

5，验证，找到build/out/apk/***.aar文件，后缀名修改为zip，解压之，可以看到jni文件夹下面编译的so文件，说明已经编译成功。