上周使用GNUstep编译android 的.so没问题，这周同样的代码和android ndk 编译失败
错误命令：
$ \d\setup\android-ndk-r9c\ndk-build \d\android\android_workspace\android-test-jni\jni
错误信息：
---------------------------------------------------------------------------------------------------------------------------
Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_
PROJECT
_PATH variable to point to it.
/home/braincol/workspace/android/android-ndk-r5/build/core/build-local.mk:85: *** Android NDK: Aborting . Stop.
--------------------------
猜了应该是命令写法问题，正确写法的记录一下，以备再忘记：
进入工程jni目录
$cd \d\android\android_workspace\android-test-jni\jni
调用ndk命令
$ \d\setup\android-ndk-r9c\ndk-build
或使用下面文章的写法
$D:\setup\android-ndk-r9c\ndk-build NDK_PROJECT_PATH=\d\android\android_workspace\android-test-jni NDK_APPLICATION_MK=\d\android\android_workspace\android-test-jni\jni\Application.mk
=============================参考文章======================================
http://blog.csdn.net/lincyang/article/details/45971655
记得前阵子编译so库直接使用ndk-build搞定，今天使用却报错如下：
$ ndk-build
Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.
/opt/android-ndk-r10b/build/core/build-local.mk:148: *** Android NDK: Aborting . Stop.
高人支招如下：
You need to specify 3 things.
NDK_PROJECT_PATH - the location of your project
NDK_APPLICATION_MK - the path of the Application.mk file
APP_BUILD_SCRIPT - the path to the Android.mk file
These are needed to override the default values of the build script, which expects things to be in the jni folder.
When calling ndk-build use
ndk-build NDK_PROJECT_PATH=/path/to/proj NDK_APPLICATION_MK=/path/to/Application.mk
In Application.mk add
APP_BUILD_SCRIPT := /path/to/Android.mk
首先第一步，在Application中加入Android.mk路径
比如这两个文件是同级的:
APP_BUILD_SCRIPT := Android.mk
第二步，直接编译：
$ ndk-build NDK_PROJECT_PATH=. NDK_APPLICATION_MK=Application.mk
[armeabi-v7a] Compile++ thumb: detection_and_recognition_lib <= DetectionAndRecognition.cpp
[armeabi-v7a] Prebuilt : libopencv_java.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/armeabi-v7a/
[armeabi-v7a] SharedLibrary : libdetection_and_recognition_lib.so
/opt/android-ndk-r10b/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: warning: hidden symbol '__aeabi_atexit' in /opt/android-ndk-r10b/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi-v7a/thumb/libgnustl_static.a(atexit_arm.o) is referenced by DSO ./obj/local/armeabi-v7a/libopencv_java.so
[armeabi-v7a] Install : libdetection_and_recognition_lib.so => libs/armeabi-v7a/libdetection_and_recognition_lib.so
[armeabi-v7a] Prebuilt : libnative_camera_r4.3.0.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/armeabi-v7a/
[armeabi-v7a] Install : libnative_camera_r4.3.0.so => libs/armeabi-v7a/libnative_camera_r4.3.0.so
[armeabi-v7a] Prebuilt : libnative_camera_r4.4.0.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/armeabi-v7a/
[armeabi-v7a] Install : libnative_camera_r4.4.0.so => libs/armeabi-v7a/libnative_camera_r4.4.0.so
[armeabi-v7a] Install : libopencv_java.so => libs/armeabi-v7a/libopencv_java.so
[x86] Compile++ : detection_and_recognition_lib <= DetectionAndRecognition.cpp
[x86] Prebuilt : libopencv_java.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/x86/
[x86] SharedLibrary : libdetection_and_recognition_lib.so
[x86] Install : libdetection_and_recognition_lib.so => libs/x86/libdetection_and_recognition_lib.so
[x86] Prebuilt : libnative_camera_r4.3.0.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/x86/
[x86] Install : libnative_camera_r4.3.0.so => libs/x86/libnative_camera_r4.3.0.so
[x86] Prebuilt : libnative_camera_r4.4.0.so <= /home/linc/workspace/lab/OpenCV-android-sdk-2.4.11/sdk/native/jni/../libs/x86/
[x86] Install : libnative_camera_r4.4.0.so => libs/x86/libnative_camera_r4.4.0.so
[x86] Install : libopencv_java.so => libs/x86/libopencv_java.so
各位大虾也许看出来了，我在编译OpenCV相关的项目。而现在的设备选型已经涵盖了x86架构，所以编译时要选择x86指令集编译。在Application.mk中注明如下：
APP_ABI := armeabi-v7a x86
后记：
放到jni目录下就不用此命令了！
参考：
http://stackoverflow.com/questions/14156596/ndk-cant-find-the-application-directory
