一、ndk下载

NDK 下载  |  Android NDK  |  Android Developers

二、ndk环境变量配置

ndk解压：

unzip android-ndk-r26d-linux.zip 

环境变量配置：

 export NDK_HOME=/rd/own/test/android-ndk-r26d/
 export PATH=$PATH:$NDK_HOME

三、编译测试验证

3.1 程序创建

创建helloworld， 在其下创建jni目录，并准备好hello.c和Android.mk

rd@ubuntu:~/test/android-ndk-r26d$ cat helloword/jni/hello.c
#include <stdio.h>
int main (int argc,char *argv[])
{printf("hello world!");return 0;
}
rd@ubuntu:~/test/android-ndk-r26d$ cat helloword/jni/Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := helloworld
LOCAL_SRC_FILES := hello.c
#include $(BUILD_SHARED_LIBRARY)
include $(BUILD_EXECUTABLE)

编译库文件Android.mk参考：
LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE := FRE
LOCAL_SRC_FILES := FlashRuntime.so
include $(PREBUILT_SHARED_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := NativeQCAR
LOCAL_SRC_FILES := main.c
LOCAL_SHARED_LIBRARIES := FRE
include $(BUILD_SHARED_LIBRARY)

备注：如果不创建jni目录，会报NDK_PROJECT_PATH 找不到。

Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.

如果不创建jni目录，则需要添加额外的配置（ NDK_PROJECT_PATH、NDK_APPLICATION_MK和APP_BUILD_SCRIP），如下：

ndk-build NDK_PROJECT_PATH=/rd/test/android-ndk-r26d/helloword  NDK_APPLICATION_MK=/rd/test/android-ndk-r26d/Application.mk
cat Application.mk
APP_BUILD_SCRIPT := /rd/test/android-ndk-r26d/helloword/Android.mk

3.2 编译过程

~/test/android-ndk-r26d/build/ndk-build

Android NDK: APP_PLATFORM not set. Defaulting to minimum supported version android-21.
[arm64-v8a] Compile        : helloworld <= hello.c
[arm64-v8a] Executable     : helloworld
[arm64-v8a] Install        : helloworld => libs/arm64-v8a/helloworld
[armeabi-v7a] Compile thumb  : helloworld <= hello.c
[armeabi-v7a] Executable     : helloworld
[armeabi-v7a] Install        : helloworld => libs/armeabi-v7a/helloworld
[x86] Compile        : helloworld <= hello.c
[x86] Executable     : helloworld
[x86] Install        : helloworld => libs/x86/helloworld
[x86_64] Compile        : helloworld <= hello.c
[x86_64] Executable     : helloworld
[x86_64] Install        : helloworld => libs/x86_64/helloworld

3.3 编译结果，默认会编译出不同架构的可执行文件

./helloword/libs/arm64-v8a/helloworld
./helloword/libs/x86/helloworld
./helloword/libs/x86_64/helloworld
./helloword/libs/armeabi-v7a/helloworld
./helloword/obj/local/arm64-v8a/objs/helloworld
./helloword/obj/local/arm64-v8a/helloworld
./helloword/obj/local/x86/objs/helloworld
./helloword/obj/local/x86/helloworld
./helloword/obj/local/x86_64/objs/helloworld
./helloword/obj/local/x86_64/helloworld
./helloword/obj/local/armeabi-v7a/objs/helloworld
./helloword/obj/local/armeabi-v7a/helloworld
 

3.4 测试执行

adb push  helloworld /data
data/helloworld
hello world!

3.5 编译说明

也可选择其他编译选项：

在jni目录或者helloword目录下执行:

ndk-build APP_ABI=all          //编译所有平台
ndk-build APP_ABI=armeabi-v7a  //编译armv7
ndk-build APP_ABI=mips         //编译mips

ndk-build APP_ABI=arm64-v8a //编译armv8A

其他ABI编译参考：build/cmake/abis.cmake

~/test/android-ndk-r26d/build/ndk-build // 默认多架构编译

生成的可执行文件在helloworld/libs或者helloword/obj下，不同平台对应不同的目录。