一、CMake 是什么

• CMake 是一个跨平台的自动化构建系统，它使用配置文件 CMakeLists.txt 来管理软件构建过程。
• CMake 基于 Makefile 做了二次开发。

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二、单个文件目录

# CMake 最低版本号要求
cmake_minimum_required(VERSION 3.16.3)

# 工程名
project(CMakeSingle)

# 变量赋值
set(SRC_LIST main.cpp)
set(SRC_LIST2 main2.cpp)

# 输出信息
message(STATUS "this is binary dir" ${PROJECT_BINARY_DIR})
message(STATUS "this is source dir" ${PROJECT_SOURCE_DIR})

# 生产执行文件名 
add_executable(main ${SRC_LIST})
add_executable(main2 ${SRC_LIST2})

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三、子目录

cmake_minimum_required(VERSION 3.16.3)

project(CMakeSub)

message(STATUS "PROJECT_BINARY_DIR " ${PROJECT_BINARY_DIR})
message(STATUS "PROJECT_SOURCE_DIR " ${PROJECT_SOURCE_DIR})
message(STATUS "CMAKE_CURRENT_SOURCE_DIR " ${CMAKE_CURRENT_SOURCE_DIR})

# 添加子目录
add_subdirectory(src)

cmake_minimum_required(VERSION 3.16.3)

message(STATUS "PROJECT_BINARY_DIR " ${PROJECT_BINARY_DIR})
message(STATUS "PROJECT_SOURCE_DIR " ${PROJECT_SOURCE_DIR})
message(STATUS "CMAKE_CURRENT_SOURCE_DIR " ${CMAKE_CURRENT_SOURCE_DIR})

SET(SRC_LIST main.cpp)

add_executable(main ${SRC_LIST})
add_executable(main2 ${SRC_LIST})

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四、多个文件目录，子目录编译成库文件

cmake_minimum_required(VERSION 3.16.3)

project(CMakeMany1)

add_subdirectory(src)

cmake_minimum_required(VERSION 3.16.3)

message(STATUS "CMAKE_CURRENT_SOURCE_DIR ->" ${CMAKE_CURRENT_SOURCE_DIR})

SET(SRC_LIST main.cpp)

# 添加 dir1 头文件路径
include_directories("${CMAKE_CURRENT_SOURCE_DIR}/dir1") # 或 include_directories(dir1) 相对路径的方式
# 添加 dir1 子目录
add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/dir1")

# 添加 dir2 头文件路径
include_directories("${CMAKE_CURRENT_SOURCE_DIR}/dir2")
# 添加 dir2 子目录
add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/dir2")


add_executable(zcoder ${SRC_LIST})
target_link_libraries(zcoder dir1 dir2)

# 安装目录到某个路径，
# 默认路径：/usr/local/
# 指定路径：cmake -DCMAKE_INSTALL_PREFIX=/../build/ ..

# 将执行文件安装到 bin 目录
install(TARGETS zcoder RUNTIME DESTINATION bin)
# 将目录安装到指定位置
install(DIRECTORY ../doc/ DESTINATION share/doc/)

# 加载所有的源码
aux_source_directory(. DIR_SRCS) # <=> set(DIR_SRCS dir1.cpp dir11.cpp)

# 默认是静态库 .a
# add_library(dir1 SHARED ${DIR_SRCS}) 动态库 .so
add_library(dir1 ${DIR_SRCS})

aux_source_directory(. DIR_SRCS)

add_library(dir2 ${DIR_SRCS})

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五、多个文件目录，子目录使用源码编译

cmake_minimum_required(VERSION 3.16.3)

project(CMakeMany2)

add_subdirectory(src)

cmake_minimum_required(VERSION 3.16.3)

set(SRC_LIST main.cpp)

# 设置子目录
set(SUB_DIR_LIST "${CMAKE_CURRENT_SOURCE_DIR}/dir1" "${CMAKE_CURRENT_SOURCE_DIR}/dir2")

foreach(SUB_DIR ${SUB_DIR_LIST})
    # 自动添加头文件
    include_directories(${SUB_DIR})
    # 遍历源文件
    aux_source_directory(${SUB_DIR} SRC_LIST)
    
    message(STATUS "SUB_DIR -> " ${SUB_DIR})
    message(STATUS "SUB_LSIT" -> ${SRC_LIST})
endforeach()

add_executable(zcoder ${SRC_LIST})

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六、生成动态库

cmake_minimum_required(VERSION 3.16.3)
project(CMakeSHARED)

# cmake -DCMAKE_BUILD_TYPE=Release ..
# 设置 Release 版本还是 Debug 版本
if (${CMAKE_BUILD_TYPE} MATCHES "Release") # 不带 -g
    set(BuildType "Release")
    message(STATUS "Release版本")
else()                                     # 带 -g
    set(BuildType "Debug")
    message(STATUS "Debug版本")
endif()

add_compile_options(-fPIC) # 动态库必须的选项

aux_source_directory(. DIR_LIB_SRCS)

# 生成动态库
add_library(Dir1 SHARED ${DIR_LIB_SRCS})

# 设置动态库最后输出的路径
set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/${BuildType})

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七、生成静态库

# cmake -DCMAKE_INSTALL_PREFIX=/../build/ ..

cmake_minimum_required(VERSION 3.16.3)
project(CMakeSTATIC)


AUX_SOURCE_DIRECTORY(. DIR_LIB_SRCS)

ADD_LIBRARY (Dir1 STATIC ${DIR_LIB_SRCS})

# 将库文件安装到 /lib 目录
INSTALL(TARGETS Dir1 ARCHIVE DESTINATION lib)
# 将头文件安装到 /include 目录
INSTALL(FILES dir1.hpp DESTINATION include) 

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八、调用动态库、静态库

• 如果同时存在动态库和静态库，优先链接动态库。
• 强制链接静态库使用 target_link_libraries(zcoder libDir1.a)。

cmake_minimum_required(VERSION 3.16.3)
project(CMakeLink)

set(SRC_LIST main.cpp)

include_directories("${CMAKE_CURRENT_SOURCE_DIR}/lib")

link_directories("${CMAKE_CURRENT_SOURCE_DIR}/lib")

# 引用动态库
add_executable(zcoder ${SRC_LIST})
target_link_libraries(zcoder Dir1)
# target_link_libraries(zcoder libDir1) # 错误
# target_link_libraries(zcoder libDir1.so) # 正确


# 强制找静态库
# target_link_libraries(zcoder libDir1.a)

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九、find_package()

• find_package() 会查找 Findxx.cmake 文件。

cmake_minimum_required(VERSION 3.16.3)
project(CMakeFind)

set(SRC_LIST main.cpp)

add_compile_options(-std=c++11)

# 是否启用 openssl
set(ENABLE_OPENSSL true)

# 查找 openssl 是否安装 
find_package(OpenSSL REQUIRED)
if(OPENSSL_FOUND AND ENABLE_OPENSSL)
    message(STATUS "找到 openssl 库:\"${OPENSSL_INCLUDE_DIR}\"")
    # 添加 openssl 的头文件路径
    include_directories(${OPENSSL_INCLUDE_DIR})
    # 添加 ENABLE_OPENSSL 的宏定义
    add_definitions(-DENABLE_OPENSSL)
    # 将 OPENSSL_LIBRARIES 的库文件名（包含路径）追加到 LINK_LIB_LIST
    list(APPEND LINK_LIB_LIST ${OPENSSL_LIBRARIES}) 
else()
    message(STATUS "没有找到 openssl 库")
endif()

# 编译动态库
# 1. 生成动态库
add_library(${CMAKE_PROJECT_NAME}_shared SHARED ${SRC_LIST})
# 2. 链接其他库
target_link_libraries(${CMAKE_PROJECT_NAME}_shared ${LINK_LIB_LIST})
# 3. 动态库输出时，不以 xx_shared 输出，而是以 xx 输出
set_target_properties(${CMAKE_PROJECT_NAME}_shared PROPERTIES OUTPUT_NAME ${CMAKE_PROJECT_NAME})

# 编译静态库
add_library(${CMAKE_PROJECT_NAME}_static STATIC ${SRC_LIST})
target_link_libraries(${CMAKE_PROJECT_NAME}_static ${LINK_LIB_LIST})
set_target_properties(${CMAKE_PROJECT_NAME}_static PROPERTIES OUTPUT_NAME ${CMAKE_PROJECT_NAME})


add_executable(zcoder ${SRC_LIST})

target_link_libraries(zcoder ${LINK_LIB_LIST})

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