在Android源码树中增加Android Library项目并使用Android.mk文件进行编译

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#android #android mk #Makefile #编译

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本文介绍如何在Android项目中集成静态库，并通过实例演示了从创建静态库项目到应用项目引用的整个过程。涵盖Android.mk配置、资源处理及编译流程。

在Android源码树中增加Android Library项目（静态链接方式的库）。

需要为Library项目添加Android.mk文件，以便于使用mm/mmm命令进行编译。

参考资料：

跟我一起写 Makefile - ChinaUnix.net

Makefile--shell函数和make的运行

makefile中的shell语法

如何学习Android mk的原理？

答案：尝试模仿Android Build System的架构来写一套类似的Makefile。创建一个build目录下写类似的一系列mk文件，然后创建多个不同的子项目。

疑问：

1. 要理解Android MK文件是如何在脚本中直接支持一系列的命令行的，似乎Makefile中不能直接单独写命令行？

2. Makefile中的target和其中各行命令的执行的次序是怎样的？如果控制？

其实Makefile中的每一行，都是按顺序执行的，比如一些变量的定义和赋值等。

./core/package.mk:376:PACKAGES.$(LOCAL_PACKAGE_NAME).PRIVATE_KEY := $(private_key)
./core/package.mk:377:PACKAGES.$(LOCAL_PACKAGE_NAME).CERTIFICATE := $(certificate)
./core/package.mk:427:PACKAGES.$(LOCAL_PACKAGE_NAME).OVERRIDES := $(strip $(LOCAL_OVERRIDES_PACKAGES))
./core/package.mk:428:PACKAGES.$(LOCAL_PACKAGE_NAME).RESOURCE_FILES := $(all_resources)
./core/package.mk:430:PACKAGES.$(LOCAL_PACKAGE_NAME).RESOURCE_OVERLAYS := $(package_resource_overlays)
通过以上RESOURCE_OVERLAYS是否能增加对Lib资源的引用？

ant编译示例：

要让Android源码树中的App项目引用Android Library项目，则需要：

1. 指定Lib项目的中间文件在Android代码树编译输出目录下（out目录）。

比如framework-res.apk的中间目录是：target Package: framework-res (out/target/product/tf4/obj/APPS/framework-res_intermediates/)

2. 让指定的App项目通过指定引用该Lib项目则可自动引用到Lib的jar和资源。

通过在Android mk编译脚本系统中（./build/目录子目录中的脚本文件）添加编译过程和变量定义，使其能够编译特殊的Lib项目和让App项目通过特定的属性能够引用到Lib项目。

示例：创建静态库项目MyLib, 及引用该项目的应用程序项目App01。

ant debug编译App01的过程：

-set-mode-check:

-set-debug-files:

-check-env:
[checkenv] Android SDK Tools Revision 22.0.1
[checkenv] Installed at /tools/android-sdk-linux_86

-setup:
[echo] Project Name: App01
[gettype] Project Type: Application

     [echo] Creating output directories if needed...
    [mkdir] Created dir: /App01/bin
    [mkdir] Created dir: /App01/bin/res
    [mkdir] Created dir: /App01/gen
    [mkdir] Created dir: /App01/bin/classes
    [mkdir] Created dir: /App01/bin/dexedLibs
     [echo] ----------
     [echo] Resolving Dependencies for App01...
[dependency] Library dependencies:
[dependency]
[dependency] ------------------
[dependency] Ordered libraries:

（由于App01引用了MyLib静态库项目，所以到此处则先编译MyLib库，然后才断续编译App01）

MyLib库编译过程：

1. 初始化project：

-setup:
[echo] Project Name: MyLib
[gettype] Project Type: Android Library

[dependency] Library dependencies:
[dependency] No Libraries

2. 处理资源res：

-code-gen:

     [echo] Handling Resources...
     [aapt] Found new input file
     [aapt] Generating resource IDs...

（这一步生成了 R.java 文件）

3. 编译java：
-compile:
[javac] Compiling 1 source file to /MyLib/bin/classes
[echo] Creating library output jar file...

（这一步生成了jar文件）

-dex:
[echo] Library project: do not convert bytecode...

-crunch:
   [crunch] Crunching PNG Files in source dir: /MyLib/res
   [crunch] To destination dir: /MyLib/bin/res
   [crunch] Crunched 0 PNG files to update cache

-package-resources:
     [echo] Library project: do not package resources...

-package:
     [echo] Library project: do not package apk...

-post-package:

-do-debug:
     [echo] Library project: do not create apk...

至此，MyLib库编译完毕，断续编译App01项目：

-code-gen:
[mergemanifest] Merging AndroidManifest files into one.
[mergemanifest] Manifest merger disabled. Using project manifest only.
     [echo] Handling aidl files...
     [aidl] No AIDL files to compile.
     [echo] ----------
     [echo] Handling RenderScript files...
[renderscript] No RenderScript files to compile.
     [echo] ----------
     [echo] Handling Resources...
     [aapt] Generating resource IDs...
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,hdpi,,,,,,,
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,mdpi,,,,,,,
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,xxhdpi,,,,,,,

(当App项目与Lib项目有同名资源，而分别在不同的dpi目录中的话，则会出现以上overlay输出提示。这表明Lib中的资源是以overlay方式集成于App项目中来的。）
     [echo] ----------
     [echo] Handling BuildConfig class...
[buildconfig] Generating BuildConfig class.

-pre-compile:

-compile:
    [javac] Compiling 4 source files to /App01/bin/classes

-post-compile:

-obfuscate:

-dex:
      [dex] input: /App01/bin/classes
      [dex] input: /MyLib/bin/classes.jar
      [dex] input: /MyLib/libs/android-support-v4.jar
      [dex] Pre-Dexing /MyLib/bin/classes.jar -> classes-753acc10e624775a3e02bc661a597b2a.jar
      [dex] Pre-Dexing /MyLib/libs/android-support-v4.jar -> android-support-v4-e45eedfe9b2b84e819a265a649d9761c.jar
      [dex] Converting compiled files and external libraries into /App01/bin/classes.dex...
       [dx] Merged dex A (22 defs/11.3KiB) with dex B (12 defs/30.1KiB). Result is 34 defs/48.6KiB. Took 0.0s
       [dx] Merged dex A (34 defs/48.6KiB) with dex B (316 defs/355.2KiB). Result is 350 defs/495.2KiB. Took 0.1s

-crunch:
   [crunch] Crunching PNG Files in source dir: /App01/res
   [crunch] To destination dir: /App01/bin/res
   [crunch] Processing image to cache: /meizu/App01/res/drawable-hdpi/ic_foo.png => /App01/bin/res/drawable-hdpi/ic_foo.png
   [crunch]   (processed image to cache entry /App01/bin/res/drawable-hdpi/ic_foo.png: 53% size of source)
   [crunch] Processing image to cache: /App01/res/drawable-mdpi/ic_foo.png => /App01/bin/res/drawable-mdpi/ic_foo.png
   [crunch]   (processed image to cache entry /App01/bin/res/drawable-mdpi/ic_foo.png: 0% size of source)
   [crunch] Processing image to cache: /App01/res/drawable-xhdpi/ic_foo.png => /App01/bin/res/drawable-xhdpi/ic_foo.png
   [crunch]   (processed image to cache entry /App01/bin/res/drawable-xhdpi/ic_foo.png: 65% size of source)
   [crunch] Processing image to cache: /App01/res/drawable-xxhdpi/ic_foo.png => /App01/bin/res/drawable-xxhdpi/ic_foo.png
   [crunch]   (processed image to cache entry /App01/bin/res/drawable-xxhdpi/ic_foo.png: 66% size of source)
   [crunch] Crunched 4 PNG files to update cache

-package-resources:
     [aapt] Creating full resource package...
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,hdpi,,,,,,,
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,mdpi,,,,,,,
     [aapt] nothing matches overlay file ic_foo.png, for flavor ,,,,,,,,,,,,xxhdpi,,,,,,,

-package:
[apkbuilder] Current build type is different than previous build: forced apkbuilder run.
[apkbuilder] Creating App01-debug-unaligned.apk and signing it with a debug key...

-post-package:

-do-debug:
[zipalign] Running zip align on final apk...
     [echo] Debug Package: /App01/bin/App01-debug.apk
[propertyfile] Creating new property file: /App01/bin/build.prop
[propertyfile] Updating property file: /App01/bin/build.prop
[propertyfile] Updating property file: /App01/bin/build.prop
[propertyfile] Updating property file: /App01/bin/build.prop

-post-build:

debug:

BUILD SUCCESSFUL