调用内部Android.mk文件来构建预构建的库不起作用

Question

我有一个项目如下:

project/jni/Android.mk
project/jni/libA/Android.mk
project/jni/libB/Android.mk
project/lib/armeabi/libA.so
project/lib/armeabi/libB.so

我的libA和libB在我的主Android.mk上设置为预构建的库,因为我不希望每次构建我的主Android.mk时都构建它们.这是我有的:

LOCAL_PATH := $(call my-dir)

###########################################    
# Declare the prebuilt A library    
###########################################
include $(CLEAR_VARS)
LOCAL_MODULE := A-prebuilt
LOCAL_SRC_FILES := ../lib/$(TARGET_ARCH_ABI)/libA.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/libA
include $(PREBUILT_SHARED_LIBRARY)

###########################################    
# Declare the prebuilt B library    
###########################################    
include $(CLEAR_VARS)     
LOCAL_MODULE := B-prebuilt    
LOCAL_SRC_FILES := ../lib/$(TARGET_ARCH_ABI)/libB.so    
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/libB/include    
include $(PREBUILT_SHARED_LIBRARY)        

###########################################    
# Declare our main module    
###########################################    
include $(CLEAR_VARS)
LOCAL_MODULE := libjnimain    
LOCAL_SRC_FILES := \    
    main.c

# for logging
LOCAL_LDLIBS    += -llog

# include the prebuilt libraries    
LOCAL_SHARED_LIBRARIES := \
A-prebuilt \    
B-prebuilt

#This will include all Android.mk files in sub-directories 
#of the current build file's path.
include $(call all-subdir-makefiles)    
include $(BUILD_SHARED_LIBRARY)

我遇到的主要问题是构建预构建库.我似乎无法通过调用他们的Android.mk来构建libA或libB,因为当我执行主要的Android.mk被调用时.任何帮助,将不胜感激.

Answer 1

顾名思义,预构建的库永远不会被构建(它们已经构建完成).如果您需要再次构建预构建的库,则需要使用BUILD_SHARED_LIBRARY包含其源并更改Android.mk以使用这些源再次构建这些模块.但是,您可以将整个库源代码树包含在一个libs文件夹中,并将其包含在Android.mk中.

请注意,您添加的库仅在源更改时才构建,并且不会受到其他模块更改的影响.

一个基本的例子如下:

首先是项目的布局.有3个模块:

• ver:这是一个库:libver.so.来源包括在内.作为ndk-build的一部分构建
• magic:这是一个预建的库:libmagic.so
• getver:正在构建的可执行文件

文件布局:

sdk@AndroidDev:~/ndk/sources/getver$ find jni/
jni/
jni/getver.c
jni/libs
jni/libs/libver
jni/libs/libver/compiled_ver.c
jni/libs/libver/Android.mk
jni/libs/libver/ver.h
jni/libs/libmagic.so
jni/libs/Android.mk
jni/Android.mk

接下来,顶级Android.mk(它在jni /中):

sdk@AndroidDev:~/ndk/sources/getver$ cat jni/Android.mk
LOCAL_PATH := $(call my-dir)
my_LOCAL_PATH := $(LOCAL_PATH)

# Include all libs (built and prebuilt)
include $(LOCAL_PATH)/libs/Android.mk

# Build my executable
LOCAL_PATH := $(my_LOCAL_PATH)
include $(CLEAR_VARS)
LOCAL_MODULE    := getver
LOCAL_SRC_FILES := getver.c
LOCAL_SHARED_LIBRARIES= ver magic
include $(BUILD_EXECUTABLE)

jni/libs/Android.mk,包含所有库:

sdk@AndroidDev:~/ndk/sources/getver$ cat jni/libs/Android.mk
LOCAL_PATH := $(call my-dir)

# Prebuilt Lib
include $(CLEAR_VARS)
LOCAL_MODULE := magic
LOCAL_SRC_FILES := libmagic.so
include $(PREBUILT_SHARED_LIBRARY)

# Lib to be built as part of building process.
include $(CLEAR_VARS)
include $(LOCAL_PATH)/libver/Android.mk

最后,Android.mk的libver.so(jni/libs/libver/Android.mk):

sdk@AndroidDev:~/ndk/sources/getver$ cat jni/libs/libver/Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := ver
LOCAL_HDR_FILES := ver.h
LOCAL_SRC_FILES := compiled_ver.c
include $(BUILD_SHARED_LIBRARY)

在上面的例子中,libmagic.so永远不会被构建,因为它是一个预构建的lib.但是,每次libver源更改时都会构建libver.so.如果getver源更改,则不会重建它.下面的插图示例(我使用touch命令来模拟getver.c源代码中的更改):

第一次构建:

sdk@AndroidDev:~/ndk/sources/getver$ ../../ndk-build
Gdbserver      : [arm-linux-androideabi-4.4.3] libs/armeabi/gdbserver
Gdbsetup       : libs/armeabi/gdb.setup
Compile thumb  : getver <= getver.c
Compile thumb  : ver <= compiled_ver.c
SharedLibrary  : libver.so
Executable     : getver
Install        : getver => libs/armeabi/getver
Prebuilt       : libmagic.so <= jni/libs/
Install        : libmagic.so => libs/armeabi/libmagic.so
Install        : libver.so => libs/armeabi/libver.so

模拟getver模块源的编辑:

sdk@AndroidDev:~/ndk/sources/getver$ touch jni/getver.c

重建(注意libver.so 没有重建):

sdk@AndroidDev:~/ndk/sources/getver$ ../../ndk-build
Gdbserver      : [arm-linux-androideabi-4.4.3] libs/armeabi/gdbserver
Gdbsetup       : libs/armeabi/gdb.setup
Compile thumb  : getver <= getver.c
Executable     : getver
Install        : getver => libs/armeabi/getver
Install        : libmagic.so => libs/armeabi/libmagic.so
Install        : libver.so => libs/armeabi/libver.so

模拟libver.so源代码的编辑

sdk@AndroidDev:~/ndk/sources/getver$ touch jni/libs/libver/compiled_ver.c

重建(通知getver重建,因为它依赖于libver.so:

sdk@AndroidDev:~/ndk/sources/getver$ ../../ndk-build
Gdbserver      : [arm-linux-androideabi-4.4.3] libs/armeabi/gdbserver
Gdbsetup       : libs/armeabi/gdb.setup
Compile thumb  : ver <= compiled_ver.c
SharedLibrary  : libver.so
Executable     : getver
Install        : getver => libs/armeabi/getver
Install        : libmagic.so => libs/armeabi/libmagic.so
Install        : libver.so => libs/armeabi/libver.so