如何更新安卓 jni 代码更改

How to update Android jni code changings

本文关键字：jni 代码 何更新 更新      更新时间：2023-10-16

目前我正在开发一个应用程序，其中包含一个由Java和本机C ++代码组成的库。因为库项目是一个 Eclipse 项目，所以我在 Eclipse 中导入了它，创建了带有"添加本机支持"功能的 Android.mk 和 Application.mk，然后将项目重新导入到 Android Studio 中。

我启动了该应用程序，它:)工作得很好但是现在，如果我想在本机 c++ 代码中进行一些更改，我认识到如果我重新启动项目，应用程序不会显示这些更改。

我将我的解决方案与谷歌的许多示例项目(例如"hello-jni"(进行了比较，在那里我的更改立即被识别并显示在智能手机上。

我看到的唯一区别是 Android.mk 文件，这对于谷歌示例来说非常简单，而对于我的项目库来说非常大......只有作为一个Java开发人员，我发现有点难以理解，这个文件在做什么以及如何修改它。它如下所示。

    LOCAL_PATH := $(call my-dir)
$(info TARGET_ARCH_ABI is $(TARGET_ARCH_ABI))
$(info LOCAL_PATH is $(LOCAL_PATH))
PREBUILT_LIBS := $(LOCAL_PATH)/../libs/libraryWithNativeCode/prebuilt/android-$(TARGET_ARCH_ABI)
include $(CLEAR_VARS)
LOCAL_MODULE := libraryWithNativeCode-sdk-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libraryWithNativeCode-sdk.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := png-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libpng.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/../libs/libraryWithNativeCode/png
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := curl-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libcurl.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/../libs/libraryWithNativeCode/curl/android-$(TARGET_ARCH_ABI)
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := ssl-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libssl.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := crypto-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libcrypto.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := http-parser-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libhttp-parser.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/../libs/libraryWithNativeCode/http-parser
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := jpeg-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libjpeg.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := turbojpeg-lib
LOCAL_SRC_FILES := $(PREBUILT_LIBS)/libturbojpeg.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/../libs/libraryWithNativeCode/jpeg-turbo
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := libraryWithNativeCode-mobile-example-app
LOCAL_LDLIBS := -llog -landroid -lEGL -lGLESv2 -lz -lm
LOCAL_LDLIBS += -fuse-ld=bfd
LOCAL_STATIC_LIBRARIES := libraryWithNativeCode-sdk-lib png-lib curl-lib ssl-lib crypto-lib http-parser-lib jpeg-lib turbojpeg-lib android_native_app_glue ndk_helper
LOCAL_CFLAGS += -Wall -Wno-unknown-pragmas -Wno-sign-compare -Wno-format-security -Wno-reorder
#LOCAL_CFLAGS += -Werror
ifdef COMPILE_CPP_11
  $(info Configured for C++11)
  LOCAL_CPPFLAGS += -DCOMPILE_CPP_11=1 -std=c++11
else
  $(info Configured for C++0x)
endif
os_name:=$(shell uname -s)
get_android_cpp_files_cmd := find $(LOCAL_PATH) -type f  -iname "*.cpp"
get_android_includes_cmd  := find $(LOCAL_PATH) -type d
get_shared_cpp_files_cmd  := find $(LOCAL_PATH)/src -type f  -iname "*.cpp"
get_shared_includes_cmd   := find $(LOCAL_PATH)/src -type d
get_platform_includes_cmd := find $(LOCAL_PATH)/../libs/libraryWithNativeCode/platform -type d ! -path "*/OSX/*" ! -path "*/iOS/*"

ifeq ($(os_name),Darwin)
    cppfiles := ${shell ${get_android_cpp_files_cmd}}
    cppfiles += ${shell ${get_shared_cpp_files_cmd}}
    includes := ${shell ${get_android_includes_cmd}}
    includes += ${shell ${get_shared_includes_cmd}}
    includes += ${shell ${get_platform_includes_cmd}}
else
    # assume windows if not specified for now (due to no uname)
    cppfiles := ${shell sh -c '${get_android_cpp_files_cmd}'}
    cppfiles += ${shell sh -c '${get_shared_cpp_files_cmd}'}
    includes := ${shell sh -c '${get_android_includes_cmd}'}
    includes += ${shell sh -c '${get_shared_includes_cmd}'}
    includes += ${shell sh -c '${get_platform_includes_cmd}'}
endif

LOCAL_SRC_FILES := $(cppfiles:$(LOCAL_PATH)/%=%)
LOCAL_C_INCLUDES := $(includes)
LOCAL_C_INCLUDES += $(LOCAL_PATH)/../libs/libraryWithNativeCode/rapidjson
LOCAL_C_INCLUDES += $(LOCAL_PATH)/../libs/libraryWithNativeCode/rapidjson/internal
include $(BUILD_SHARED_LIBRARY)
$(call import-module,android/native_app_glue)
$(call import-module,android/ndk_helper)

我的文件夹结构是这样的：

- Android_Studio_Project
--.gradle
--.idea
--app
---src
----main (etc)
--libraryProjectWithNativeCode
---src
----main
-----java (contains the java code)
-----jni (contains the jni code)
-----jniLibs
-----etc.
--build.gradle etc.

有人知道如何解决这个问题吗？提前致谢:)

没问题。 $(cppfiles)是动态收集的C++源文件列表。您无需手动更新此列表。只需调用ndk-build即可重建本机部分。

目前Android Studio会即时创建一个新的Makefile，并从jni/编译所有源代码。不幸的是，它无法处理预编译的库文件。

来自 gradle 的更好的 NDK 支持应该很快就会发布，但与此同时，您可以停用当前的支持，并自行调用 ndk-build：

android {
    sourceSets.main {
        jni.srcDirs = [] //disable the built-in ndk-build call with auto-generated Android.mk
    }
}

ndk-build 会将生成的 .so 文件放在 libs/armeabi,x86,... 文件夹中，但 Android Studio 希望它们放在 jniLibs/armeabi,x86,... 中。调用 ndk-build 后，您可以手动移动它们，或者更改jniLibs目录的位置，如下所示：

android {
    sourceSets.main {
        jniLibs.srcDir 'src/main/libs' //set libs as .so's location instead of jniLibs
        jni.srcDirs = [] //disable the built-in ndk-build call with auto-generated Android.mk
    }
}

如果你愿意，你甚至可以让 ndk-build 被 gradle 调用：

import org.apache.tools.ant.taskdefs.condition.Os
...     
android {
    ...
    sourceSets.main {
        jniLibs.srcDir 'src/main/libs' //set libs as .so's location instead of jniLibs
        jni.srcDirs = [] //disable automatic ndk-build call with auto-generated Android.mk
    }
    // call regular ndk-build(.cmd) script from app directory
    task ndkBuild(type: Exec) {
        if (Os.isFamily(Os.FAMILY_WINDOWS)) {
            commandLine 'ndk-build.cmd', '-C', file('src/main').absolutePath
        } else {
            commandLine 'ndk-build', '-C', file('src/main').absolutePath
        }
    }
    tasks.withType(JavaCompile) {
        compileTask -> compileTask.dependsOn ndkBuild
    }
}
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