Android开发之Android.mk模板的实例详解
作者:Jhuster
Android开发之Android.mk模板的实例详解
关于Android NDK开发的文章已经比较多了,我的博客中也分享了很多NDK开发相关经验和技巧,今天简单写了一个 Android.mk 的示例模板,供初学者参考。
本模板主要给大家示例 Android NDK 开发中的如下几个问题:
1. 如何自动添加需要编译的源文件列表
2. 如何添加第三方静态库、动态库的依赖
3. 如何构造一个完整的NDK工程框架
假设我们的项目依赖 libmath.a, libjson.a, libffmpeg.so 这几个第三方库文件,项目包含如下几个模块:algorithm,core,network,utils,tests,每个模块都有若干个.c/.h文件,我们要把整个工程编译为动态库,并通过 native_sdk.c 中的函数向Java层提供调用接口。
那么,我们可以对 Android 工程的 jni 目录,做如下划分:
对应的 Android.mk 文件的写法示例如下(注:工程文件可以到我的Github(@Jhuster/Android)中在线查看,也可以在本博文最后的附件中下载):
LOCAL_PATH := $(call my-dir) 3RD_INC_DIR = $(LOCAL_PATH)/3rd/inc 3RD_LIB_DIR = $(LOCAL_PATH)/3rd/libs # Prebuild the 3rd libraries include $(CLEAR_VARS) LOCAL_MODULE := math LOCAL_SRC_FILES := $(3RD_LIB_DIR)/libmath.a include $(PREBUILT_STATIC_LIBRARY) include $(CLEAR_VARS) LOCAL_MODULE := json LOCAL_SRC_FILES := $(3RD_LIB_DIR)/libjson.a include $(PREBUILT_STATIC_LIBRARY) include $(CLEAR_VARS) LOCAL_MODULE := ffmpeg LOCAL_SRC_FILES := $(3RD_LIB_DIR)/libffmpeg.so include $(PREBUILT_SHARED_LIBRARY) # Build native sdk include $(CLEAR_VARS) LOCAL_MODULE := native_sdk LOCAL_SRC_FILES := \ $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/src/algorithm/*.c)) \ $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/src/core/*.c)) \ $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/src/network/*.c)) \ $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/src/utils/*.c)) \ $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/src/*.c)) LOCAL_C_INCLUDES := $(3RD_INC_DIR) LOCAL_C_INCLUDES := $(LOCAL_PATH)/src LOCAL_C_INCLUDES := $(LOCAL_PATH)/src/algorithm LOCAL_C_INCLUDES += $(LOCAL_PATH)/src/core LOCAL_C_INCLUDES += $(LOCAL_PATH)/src/network LOCAL_C_INCLUDES += $(LOCAL_PATH)/src/utils LOCAL_CFLAGS := -DANDROID LOCAL_LDLIBS := -llog LOCAL_STATIC_LIBRARIES := math json LOCAL_SHARED_LIBRARIES := ffmpeg include $(BUILD_SHARED_LIBRARY) # Build tests include $(CLEAR_VARS) LOCAL_MODULE := test.out LOCAL_SRC_FILES := $(subst $(LOCAL_PATH)/,,$(wildcard $(LOCAL_PATH)/tests/*.c)) LOCAL_CFLAGS := -DANDROID LOCAL_C_INCLUDES := $(LOCAL_PATH)/src LOCAL_LDLIBS := -llog -fPIE -pie LOCAL_SHARED_LIBRARIES:= native_sdk include $(BUILD_EXECUTABLE)
对于 Android.mk 而言,如果要依赖第三方库文件,则必须添加 PREBUILT_XXXX_LIBRARY 进行预编译,LOCAL_SRC_FILES 宏给出了需要编译的源文件列表,这里我通过 subst和wildcard 这两个函数,实现了自动扫描指定目录下的源文件,最后,通过 BUILD_EXECUTABLE 编译出可以运行于adb shell命令行的可执行程序,用于做代码的单元测试。
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