android ndk Application.mk

Application.mk

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Overview
Variables

This document explains the 

Application.mk

 build file, which describes the native modules that your app requires. A module can be a static library, a shared library,
or an executable可执行的.
We recommend that you read the Concepts and Android.mk pages
before this one. Doing so will help maximize your understanding of the material材料 on this page.

Application.mk

Application.mk目的是描述在你的应用程序中所需要的模块(即静态库或动态库)。

变量	描述
APP_PROJECT_PATH	这个变量是强制性的，并且会给出应用程序工程的根目录的一个绝对路径。
APP_MODULES	这个变量是可选的，如果没有定义，NDK将由在Android.mk中声明的默认的模块编译，并且包含所有的子文件（makefile文件）如果APP_MODULES定义了，它不许是一个空格分隔的模块列表，这个模块名字被定义在Android.mk文件中的LOCAL_MODULE中。
APP_OPTIM	这个变量是可选的，用来义“release”或"debug"。在编译您的应用程序模块的时候，可以用来改变优先级。
APP_CFLAGS	当编译模块中有任何C文件或者C++文件的时候，C编译器的信号就会被发出。
APP_CXXFLAGS	APP_CPPFLAGS的别名，已经考虑在将在未来的版本中废除了
APP_CPPFLAGS	当编译的只有C++源文件的时候，可以通过这个C++编译器来设置
APP_BUILD_SCRIPT	默认情况下，NDK编译系统会在$(APP_PROJECT_PATH)/jni目录下寻找名为Android.mk文件： $(APP_PROJECT_PATH)/jni/Android.mk
APP_ABI	默认情况下，NDK的编译系统回味"armeabi"ABI生成机器代码。
APP_STL	默认情况下，NDK的编译系统为最小的C++运行时库（/system/lib/libstdc++.so）提供C++头文件。然而，NDK的C++的实现，可以让你使用或着链接在自己的应用程序中。 例如： APP_STL := stlport_static    --> static STLport library APP_STL := stlport_shared    --> shared STLport library APP_STL := system            --> default C++ runtime library

Overview概述

The 

Application.mk

 file is really a tiny GNU Makefile fragment that defines several variables for compilation编译. It usually resides存在 under 

$PROJECT/jni/

, where 

$PROJECT

 points to your application's
project directory. Another alternative（二中择一；供替代的选择） is to place it under a sub-directory of the top-level 

$NDK/apps/

 directory. For example:

$NDK/apps/<myapp>/Application.mk

Here, 

<myapp>

 is a short name used to describe your app to the NDK build system. It doesn't actually go into your generated shared libraries or your final packages.

Variables变量函数

APP_PROJECT_PATH

This variable stores the absolute path to your app's project-root directory. The build system uses this information to place stripped-down定制 versions of the generated JNI shared libraries into a specific location
known to the APK-generating tools.
If you place放置 your 

Application.mk

 file under 

$NDK/apps/<myapp>/

, you must define this variable. If you place it under 

$PROJECT/jni/

,
it is optional.

APP_OPTIM

Define this optional variable as either 

release

 or 

debug

. You use it to alter改动 the optimization最佳化，最优化 level when building your application's modules.
Release mode is the default, and generates highly optimized binaries. Debug mode generates unoptimized binaries that are much easier to debug.
Note that you can debug either release or debug binaries. Release binaries, however, provide less information during debugging. For example, the build system optimizes out优化了 some variables, preventing you from
inspecting检查 them. Also, code re-ordering重组 can make it more difficult to step through the code; stack traces堆栈跟踪 may not be reliable可靠.
Declaring 

android:debuggable

 in your application manifest's 

<application>

 tag will cause this variable to default to 

debug

 instead of 

release

.
Override this default value by setting 

APP_OPTIM

 to 

release

.

APP_CFLAGS

This variable stores a set of C compiler flags that the build system passes to the compiler when compiling any C or C++ source code for any of the modules. You can use this variable to change the build of a given
module according根据 to the application that needs it, instead of having to modify the 

Android.mk

 file itself.
All paths in these flags should be relative to the top-level NDK directory. For example, if you have the following setup:

sources/foo/Android.mk
sources/bar/Android.mk

To specify指定 in 

foo/Android.mk

 that you want to add the path to the 

bar

 sources during compilation, you should use:

APP_CFLAGS += -Isources/bar

Or, alternatively:

APP_CFLAGS += -I$(LOCAL_PATH)/../bar

-I../bar

 will not work since it is equivalent等价 to 

-I$NDK_ROOT/../bar

.

Note: This variable only works on C, not C++, sources in android-ndk-1.5_r1. In all versions after that one,

APP_CFLAGS

 matches the full Android build system.

APP_CPPFLAGS

This variable contains a set of C++ compiler flags that the build system passes to the compiler when building only C++ sources.

Note: In android-ndk-1.5_r1, this variable works on both C and C++ sources. In all subsequent（随后的后来的后面的
 ） versions of the NDK, 

APP_CPPFLAGS

 now matches the full Android build system. For flags that apply to both C and C++ sources,
use 

APP_CFLAGS

.

APP_LDFLAGS

A set of linker flags that the build system passes when linking the application. This variable is only relevant相关的 when the build system is building shared libraries and executables. When the build system builds
static libraries, it ignores these flags.

APP_BUILD_SCRIPT

By default, the NDK build system looks under 

jni/

 for a file named 

Android.mk

.
If you want to override this behavior, you can define 

APP_BUILD_SCRIPT

 to point to an alternate build script. The build system always interprets解释 a non-absolute
path as relative to the NDK's top-level directory.

APP_ABI

By default, the NDK build system generates machine code for the 

armeabi

 ABI.
This machine code corresponds to an ARMv5TE-based CPU with software floating point operations. You can use 

APP_ABI

 to select a different ABI. Table 1 shows the 

APP_ABI

 settings for different instruction sets.
Table 1. 

APP_ABI

 settings for different instruction sets.

Instruction set	Value
Hardware FPU instructions on ARMv7 based devices	APP_ABI := armeabi-v7a
ARMv8 AArch64	APP_ABI := arm64-v8a
IA-32	APP_ABI := x86
Intel64	APP_ABI := x86_64
MIPS32	APP_ABI := mips
MIPS64 (r6)	APP_ABI := mips64
All supported instruction sets	APP_ABI := all

Note: 

all

 is available starting from NDKr7.
You can also specify multiple values by placing them on the same line, delimited by spaces. For example:

APP_ABI := armeabi armeabi-v7a x86 mips

For the list of all supported ABIs and details about their usage and limitations, refer to ABI
Management.

APP_PLATFORM

This variable contains the name of the target Android platform. For example, 

android-3

 specifies the Android 1.5 system images. For a complete list of platform names and corresponding Android
system images, seeAndroid NDK Native APIs .

APP_STL

By default, the NDK build system provides C++ headers for the minimal C++ runtime library (

system/lib/libstdc++.so

) provided by the Android system. In addition, it comes with alternative C++
implementations that you can use or link to in your own applications. Use 

APP_STL

 to select one of them. For information about the supported runtimes, and the features they offer, see NDK
Runtimes and Features.

APP_SHORT_COMMANDS

The equivalent相等的 of 

LOCAL_SHORT_COMMANDS

 in 

Application.mk

 for your whole project. For more information, see the documentation for this
variable on 

Android.mk

.

NDK_TOOLCHAIN_VERSION

Define this variable as either 

4.9

 or 

4.8

 to select a version of the GCC compiler.Version 4.9 is the default for
64-bit ABIs, and 4.8 is the default for 32-bit ABIs. To select a version of Clang, define this variable as 

clang3.4

,

clang3.5

, or 

clang

. Specifying 

clang

 chooses
the most recent version of Clang.

APP_PIE

Starting from Android 4.1 (API level 16), Android's dynamic动态 linker supports position-independent executables (PIE). From Android 5.0 (API level 21), executables require PIE. To use PIE to build your executables,
set the 

-fPIE

 flag. This flag makes it harder to exploit开发利用 memory corruption（贪污腐败
堕落） bugs by randomizing（随机化） code location. By default,

ndk-build

 automatically sets this value to 

true

 if your project
targets 

android-16

 or higher. You may set it manually手动 to either 

true

 or 

false

.
This flag applies only to executables. It has no effect when building shared or static libraries.

Note: PIE executables cannot run on Android releases prior to 4.1.
This restriction约束 only applies to executables. It has no effect when building shared or static libraries.

APP_THIN_ARCHIVE

Sets the default value of 

LOCAL_THIN_ARCHIVE

 in the 

Android.mk

 file for all static library modules in this project. For more information, see the documentation for 

LOCAL_THIN_ARCHIVE

 on 

Android.mk

.