Android Makefile文件：Android.mk写法

android编译系统的makefile文件Android.mk写法如下

1.LOCAL_PATH

Android.mk文件首先需要指定LOCAL_PATH变量，用于查找源文件。由于一般情况下Android.mk和需要编译的源文件在同一目录下，所以定义成如下形式：
LOCAL_PATH:=$(call my-dir)
上面的语句的意思是将LOCAL_PATH变量定义成本文件（当前的Android.mk）所在目录路径。
规定LOCAL_PATH必须放在所有的include $(CLEAR_VARS)之前

2.CLEAR_VARS

Android.mk中可以定义多个编译模块，每个编译模块都是以include $(CLEAR_VARS) 开始，以 include $(BUILD_XXX) 结束。

include $(CLEAR_VARS)
...
include $(BUILD_XXX)

CLEAR_VARS由编译系统提供，是一个编译模块的开始，指定让GNUMAKEFILE为你清除除LOCAL_PATH以外的所有LOCAL_XXX变量，如LOCAL_MODULE，LOCAL_SRC_FILES，LOCAL_SHARED_LIBRARIES，LOCAL_STATIC_LIBRARIES等。
BUILD_XXX描述了编译目标

include $(BUILD_STATIC_LIBRARY)表示编译成目标设备上的静态库(附录1)；
include $(BUILD_SHARED_LIBRARY)表示编译成目标设备上的动态库(附录2)；
include $(BUILD_EXECUTABLE)表示编译成目标设备上的可执行程序(附录3)；
include $(BUILD_HOST_STATIC_LIBRARY)表示编译成主机上的静态库；
include $(BUILD_HOST_SHARED_LIBRARY)表示编译成主机上的动态库；
include $(BUILD_HOST_EXECUTABLE)表示编译成主机上的可执行文件；
include $(BUILD_JAVA_LIBRARY)表示编译成JAVA库；
include $(BUILD_STATIC_JAVA_LIBRARY)表示编译成静态JAVA库；
include $(BUILD_HOST_JAVA_LIBRARY)表示编译成主机上的JAVA库；
include $()BUILD_PACKAGE表示编译成APK程序。

3.例

举例如下(frameworks/base/libs/audioflinger/Android.mk)：

LOCAL_PATH:= $(call my-dir)

#-----------------------模块一---------------------
include $(CLEAR_VARS)                    #模块一
ifeq ($(AUDIO_POLICY_TEST),true)         #ifeq ($(CC),gcc)  表示判断表达式与某个值是否相等
    ENABLE_AUDIO_DUMP := true            #这里应该是定义一个标志，仅供当前.mk文件使用
endif

#LOCAL_SRC_FILES定义了本模块编译使用的源文件，采用的是基于LOCAL_PATH的相对路径
LOCAL_SRC_FILES:= \           
    AudioHardwareGeneric.cpp \
    AudioHardwareStub.cpp \
    AudioHardwareInterface.cpp

#下面这三句是我自己加的：    
LOCAL_CFLAGS := -Wall -Wextra -Werror   #gcc的编译选项 如：gcc -Wall -Wextra -Werror main.c -o main
#LOCAL_CFLAGS += -DXXX   相当于在  所有源文件  中增加一个宏定义#define XXX
#使用“+=”操作符给变量追加值
LOCAL_CFLAGS += -DSUNDP_FLAG
LOCAL_CFLAGS += -DSUNDPMY_FLAG

#ifeq ($(CC),gcc) 代表判断$(CC)变量是否是“gcc”
#下面这句就是判断ENABLE_AUDIO_DUMP是不是ture
ifeq ($(ENABLE_AUDIO_DUMP),true)
    LOCAL_SRC_FILES += AudioDumpInterface.cpp
    LOCAL_CFLAGS += -DENABLE_AUDIO_DUMP
endif

#表示编译本模块时需要链接的动态库
LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libutils \
    libbinder \
    libmedia \
    libhardware_legacy
    
#strip
#名称：去空格函数——strip。 
#功能：去掉字串中开头和结尾的空字符。 
#返回：返回被去掉空格的字符串值。
#示例： 
#$(strip a b c ) 
#把字串“a b c ”去到开头和结尾的空格，结果是“a b c”。
ifeq ($(strip $(BOARD_USES_GENERIC_AUDIO)),true)
    LOCAL_CFLAGS += -DGENERIC_AUDIO
endif

#LOCAL_MODULE：本模块的模块名，也就是说模块一被编译成libaudiointerface.so
LOCAL_MODULE:= libaudiointerface   
ifeq ($(BOARD_HAVE_BLUETOOTH),true)
    LOCAL_SRC_FILES += A2dpAudioInterface.cpp
    LOCAL_SHARED_LIBRARIES += liba2dp
    LOCAL_CFLAGS += -DWITH_BLUETOOTH -DWITH_A2DP
    #LOCAL_C_INCLUDES：本模块需要引用的include文件
    LOCAL_C_INCLUDES += $(call include-path-for, bluez)
endif
include $(BUILD_STATIC_LIBRARY)     #模块一编译成静态库

#-----------------------模块二---------------------
include $(CLEAR_VARS)    #模块二

LOCAL_SRC_FILES:=    \
    AudioPolicyManagerBase.cpp
LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libutils \
    libmedia
    
ifeq ($(TARGET_SIMULATOR),true)
    LOCAL_LDLIBS += -ldl
else
    LOCAL_SHARED_LIBRARIES += libdl
endif

LOCAL_MODULE:= libaudiopolicybase
ifeq ($(BOARD_HAVE_BLUETOOTH),true)
    LOCAL_CFLAGS += -DWITH_A2DP
endif
ifeq ($(AUDIO_POLICY_TEST),true)
    LOCAL_CFLAGS += -DAUDIO_POLICY_TEST
endif
include $(BUILD_STATIC_LIBRARY)     #模块二编译成静态库

#-----------------------模块二---------------------
include $(CLEAR_VARS)           #模块三
LOCAL_SRC_FILES:=    \
    AudioFlinger.cpp     \
    AudioMixer.cpp.arm   \
    AudioResampler.cpp.arm   \
    AudioResamplerSinc.cpp.arm   \
    AudioResamplerCubic.cpp.arm \
    AudioPolicyService.cpp
LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libutils \
    libbinder \
    libmedia \
    libhardware_legacy
ifeq ($(strip $(BOARD_USES_GENERIC_AUDIO)),true)
    LOCAL_STATIC_LIBRARIES += libaudiointerface libaudiopolicybase
    LOCAL_CFLAGS += -DGENERIC_AUDIO
else
    LOCAL_SHARED_LIBRARIES += libaudio libaudiopolicy
endif

ifeq ($(TARGET_SIMULATOR),true)
    LOCAL_LDLIBS += -ldl
else
    LOCAL_SHARED_LIBRARIES += libdl
endif

LOCAL_MODULE:= libaudioflinger
ifeq ($(BOARD_HAVE_BLUETOOTH),true)
    LOCAL_CFLAGS += -DWITH_BLUETOOTH -DWITH_A2DP
    LOCAL_SHARED_LIBRARIES += liba2dp
endif

ifeq ($(AUDIO_POLICY_TEST),true)
    LOCAL_CFLAGS += -DAUDIO_POLICY_TEST
endif

ifeq ($(TARGET_SIMULATOR),true)
    ifeq ($(HOST_OS),linux)
        LOCAL_LDLIBS += -lrt -lpthread
    endif
endif
ifeq ($(BOARD_USE_LVMX),true)
    LOCAL_CFLAGS += -DLVMX
    LOCAL_C_INCLUDES += vendor/nxp
    LOCAL_STATIC_LIBRARIES += liblifevibes
    LOCAL_SHARED_LIBRARIES += liblvmxservice
#   LOCAL_SHARED_LIBRARIES += liblvmxipc
endif
include $(BUILD_SHARED_LIBRARY) #模块三编译成动态库

4.编译一个应用程序(APK)

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # Build all java files in the java subdirectory
  LOCAL_SRC_FILES := $(call all-subdir-java-files)
   
  # Name of the APK to build
  LOCAL_PACKAGE_NAME := LocalPackage
   
  # Tell it to build an APK
  include $(BUILD_PACKAGE)

5.编译一个依赖于静态Java库(static.jar)的应用程序

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # List of static libraries to include in the package
  LOCAL_STATIC_JAVA_LIBRARIES := static-library
   
  # Build all java files in the java subdirectory
  LOCAL_SRC_FILES := $(call all-subdir-java-files)
   
  # Name of the APK to build
  LOCAL_PACKAGE_NAME := LocalPackage
   
  # Tell it to build an APK
  include $(BUILD_PACKAGE)

6.编译一个需要用平台的key签名的应用程序

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # Build all java files in the java subdirectory
  LOCAL_SRC_FILES := $(call all-subdir-java-files)
   
  # Name of the APK to build
  LOCAL_PACKAGE_NAME := LocalPackage
   
  LOCAL_CERTIFICATE := platform
   
  # Tell it to build an APK
  include $(BUILD_PACKAGE)

7.编译一个需要用特定key前面的应用程序

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # Build all java files in the java subdirectory
  LOCAL_SRC_FILES := $(call all-subdir-java-files)
   
  # Name of the APK to build
  LOCAL_PACKAGE_NAME := LocalPackage
   
  LOCAL_CERTIFICATE := vendor/example/certs/app
   
  # Tell it to build an APK
  include $(BUILD_PACKAGE)

8.添加一个预编译应用程序

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # Module name should match apk name to be installed.
  LOCAL_MODULE := LocalModuleName
  LOCAL_SRC_FILES := $(LOCAL_MODULE).apk
  LOCAL_MODULE_CLASS := APPS
  LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
   
  include $(BUILD_PREBUILT)

9.添加一个静态JAVA库

LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
   
  # Build all java files in the java subdirectory
  LOCAL_SRC_FILES := $(call all-subdir-java-files)
   
  # Any libraries that this library depends on
  LOCAL_JAVA_LIBRARIES := android.test.runner
   
  # The name of the jar file to create
  LOCAL_MODULE := sample
   
  # Build a static jar file.
  include $(BUILD_STATIC_JAVA_LIBRARY)

10.相关的变量

Android.mk的编译模块中间可以定义相关的编译内容，也就是指定相关的变量如下：
LOCAL_AAPT_FLAGS
LOCAL_ACP_UNAVAILABLE 
LOCAL_ADDITIONAL_JAVA_DIR 
 
LOCAL_AIDL_INCLUDES 
LOCAL_ALLOW_UNDEFINED_SYMBOLS 
LOCAL_ARM_MODE 
LOCAL_ASFLAGS 
LOCAL_ASSET_DIR

LOCAL_ASSET_FILES 在Android.mk文件中编译应用程序(BUILD_PACKAGE)时设置此变量，表示资源文件，通常会定义成LOCAL_ASSET_FILES += $(call find-subdir-assets)

LOCAL_BUILT_MODULE_STEM

LOCAL_C_INCLUDES 额外的C/C++编译头文件路径，用LOCAL_PATH表示本文件所在目录
                 举例如下：
                 LOCAL_C_INCLUDES += extlibs/zlib-1.2.3
                 LOCAL_C_INCLUDES += $(LOCAL_PATH)/src

LOCAL_CC 指定C编译器
LOCAL_CERTIFICATE  签名认证
LOCAL_CFLAGS 为C/C++编译器定义额外的标志(如宏定义)，举例：LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1

LOCAL_CLASSPATH
LOCAL_COMPRESS_MODULE_SYMBOLS
LOCAL_COPY_HEADERS install应用程序时需要复制的头文件，必须同时定义LOCAL_COPY_HEADERS_TO

LOCAL_COPY_HEADERS_TO install应用程序时复制头文件的目的路径
LOCAL_CPP_EXTENSION 如果你的C++文件不是以cpp为文件后缀，你可以通过LOCAL_CPP_EXTENSION指定C++文件后缀名
                    如：LOCAL_CPP_EXTENSION := .cc
                    注意统一模块中C++文件后缀必须保持一致。
LOCAL_CPPFLAGS 传递额外的标志给C++编译器，如：LOCAL_CPPFLAGS += -ffriend-injection
LOCAL_CXX 指定C++编译器

LOCAL_DX_FLAGS
LOCAL_EXPORT_PACKAGE_RESOURCES
LOCAL_FORCE_STATIC_EXECUTABLE 如果编译的可执行程序要进行静态链接(执行时不依赖于任何动态库)，则设置LOCAL_FORCE_STATIC_EXECUTABLE:=true
                              目前只有libc有静态库形式，这个只有文件系统中/sbin目录下的应用程序会用到，这个目录下的应用程序在运行时通常
                              文件系统的其它部分还没有加载，所以必须进行静态链接。

LOCAL_GENERATED_SOURCES

LOCAL_INSTRUMENTATION_FOR
LOCAL_INSTRUMENTATION_FOR_PACKAGE_NAME
LOCAL_INTERMEDIATE_SOURCES
LOCAL_INTERMEDIATE_TARGETS
LOCAL_IS_HOST_MODULE
LOCAL_JAR_MANIFEST
LOCAL_JARJAR_RULES
LOCAL_JAVA_LIBRARIES 编译java应用程序和库的时候指定包含的java类库，目前有core和framework两种
                     多数情况下定义成：LOCAL_JAVA_LIBRARIES := core framework
                     注意LOCAL_JAVA_LIBRARIES不是必须的，而且编译APK时不允许定义(系统会自动添加)

LOCAL_JAVA_RESOURCE_DIRS
LOCAL_JAVA_RESOURCE_FILES
LOCAL_JNI_SHARED_LIBRARIES
LOCAL_LDFLAGS 传递额外的参数给连接器(务必注意参数的顺序)

LOCAL_LDLIBS 为可执行程序或者库的编译指定额外的库，指定库以"-lxxx"格式，举例：
             LOCAL_LDLIBS += -lcurses -lpthread
             LOCAL_LDLIBS += -Wl,-z,origin
 
LOCAL_MODULE 生成的模块的名称(注意应用程序名称用LOCAL_PACKAGE_NAME而不是LOCAL_MODULE)
LOCAL_MODULE_PATH 生成模块的路径
 
LOCAL_MODULE_STEM
 
LOCAL_MODULE_TAGS 生成模块的标记 
 
LOCAL_NO_DEFAULT_COMPILER_FLAGS 
LOCAL_NO_EMMA_COMPILE 
LOCAL_NO_EMMA_INSTRUMENT 
LOCAL_NO_STANDARD_LIBRARIES 
LOCAL_OVERRIDES_PACKAGES 
LOCAL_PACKAGE_NAME APK应用程序的名称 
LOCAL_POST_PROCESS_COMMAND
 
LOCAL_PREBUILT_EXECUTABLES 预编译including $(BUIL{D}_{P}REBUILT)或者$(BUILD_HOST_PREBUILT)时所用,指定需要复制的可执行文件
LOCAL_PREBUILT_JAVA_LIBRARIES 
LOCAL_PREBUILT_LIBS 预编译including $(BUIL{D}_{P}REBUILT)或者$(BUILD_HOST_PREBUILT)时所用, 指定需要复制的库.
LOCAL_PREBUILT_OBJ_FILES 
LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES  
 
LOCAL_PRELINK_MODULE 是否需要预连接处理(默认需要，用来做动态库优化)
LOCAL_REQUIRED_MODULES 指定模块运行所依赖的模块(模块安装时将会同步安装它所依赖的模块)
 
LOCAL_RESOURCE_DIR
LOCAL_SDK_VERSION
LOCAL_SHARED_LIBRARIES 可链接动态库
 
LOCAL_SRC_FILES 编译源文件
 
LOCAL_STATIC_JAVA_LIBRARIES 
LOCAL_STATIC_LIBRARIES 可链接静态库 
 
LOCAL_UNINSTALLABLE_MODULE 
LOCAL_UNSTRIPPED_PATH
 
LOCAL_WHOLE_STATIC_LIBRARIES 指定模块所需要载入的完整静态库(这些精通库在链接是不允许链接器删除其中无用的代码)
 
LOCAL_YACCFLAGS
 
OVERRIDE_BUILT_MODULE_PATH