⑴ android 怎么编译so文件
android NDK编译多个so文件
android编译系统的makefile文件Android.mk写法如下
(1)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变量定义成本文件所在目录路径。
(2)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)
CLEAR_VARS由编译系统提供，指定让GNU MAKEFILE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。
include $(BUILD_STATIC_LIBRARY)表示编译成静态库
include $(BUILD_SHARED_LIBRARY)表示编译成动态库。
include $(BUILD_EXECUTABLE)表示编译成可执行程序
(3)举例如下(frameworks/base/libs/audioflinger/Android.mk)：
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS) 模块一
ifeq ($(AUDIO_POLICY_TEST),true)
ENABLE_AUDIO_DUMP := true
endif
LOCAL_SRC_FILES:= \
AudioHardwareGeneric.cpp \
AudioHardwareStub.cpp \
AudioHardwareInterface.cpp
ifeq ($(ENABLE_AUDIO_DUMP),true)
LOCAL_SRC_FILES += AudioDumpInterface.cpp
LOCAL_CFLAGS += -DENABLE_AUDIO_DUMP
endif
LOCAL_SHARED_LIBRARIES := \
libcutils \
libutils \
libbinder \
libmedia \
libhardware_legacy
ifeq ($(strip $(BOARD_USES_GENERIC_AUDIO)),true)
LOCAL_CFLAGS += -DGENERIC_AUDIO
endif
LOCAL_MODULE:= libaudiointerface
ifeq ($(BOARD_HAVE_BLUETOOTH),true)
LOCAL_SRC_FILES += A2dpAudioInterface.cpp
LOCAL_SHARED_LIBRARIES += liba2dp
LOCAL_CFLAGS += -DWITH_BLUETOOTH -DWITH_A2DP
LOCAL_C_INCLUDES += $(call include-path-for, bluez)
endif
include $(BUILD_STATIC_LIBRARY) 模块一编译成静态库
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
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-->直译（建立在java子目录中的所有Java文件）
LOCAL_SRC_FILES := $(call all-subdir-java-files)
# Name of the APK to build-->直译（创建APK的名称）
LOCAL_PACKAGE_NAME := LocalPackage
# Tell it to build an APK-->直译（告诉它来建立一个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)
# Mole name should match apk name to be installed.
LOCAL_MODULE := LocalMoleName
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)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 $(BUILD_PREBUILT)或者$(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 $(BUILD_PREBUILT)或者$(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
⑵ 请问安卓的SO文件是怎么回事，可以反编译出源码吗 是如何生成的用JAVA还是C代码生成的
如何JAVA代码调用?
jni吧？
安卓的SO文件是linux下的文件，用c或者c++写的。
⑶ android studio JNI开发时 编译成功 但是没有生成.so文件 什么原因
1
在交叉编译的时候怎么都无法生成so文件，javah生成头文件没错，c文件也没错，java文件也没错，
2.原因：是JNI文件夹路径不对
3
在执行javah命令时，我进入的是cd
app/src/main/java
这样jni文件夹在java文件夹下，作为一个包存在，这样就无法生成so文件
执行javah的正确姿势：
4
进入app/src/main目录：cd
app/src/main
执行javah命令：javah
javah
-d
jni
-classpath
./Java
lab.sodino.jnitest.MainActivity
5，
-d
jni
头文件生成到jni文件夹（当前在<Project>\app\src\main目录下，所以.h所在的目录为<Project>\app\src\main\jni
）
-classpath
./java
指定去当前路径下java下寻找包名指定的类
这样再rebuild一下，就会生成so文件了