CMake 实例学习（3）构建静态库

1：概述
   有了上一节共享库的工作，这节的就简单多了。

2: 目录结构

[onezeroone@ ex-4]$ tree
.
 build
 CMakeLists.txt
 lib
  CMakeLists.txt
  hello.c
  hello.h
 src
     CMakeLists.txt
     main.c

3 directories, 6 files

3：文件内容
   这里就不罗嗦了，直接看内容吧，参考前面共享库的制作，需要稍作修改就OK。

[onezeroone@ ex-4]$ cat CMakeLists.txt
PROJECT(EX-4)
ADD_SUBDIRECTORY(lib)

现在是制作静态库时的状态，使用静态库的时候我们需要稍作修改。

[onezeroone@ ex-4]$ cat ./lib/CMakeLists.txt
SET(LIBHELLO_SRC hello.c)
ADD_LIBRARY(hello STATIC ${LIBHELLO_SRC})
INSTALL(TARGETS hello
        ARCHIVE DESTINATION lib)
INSTALL(FILES hello.h DESTINATION include/hello)

需要修改只有2处，STATIC表示要生成静态库，ARCHIVE表示指定静态库的路径。hello文件跟上一节一样。

跟上一节一样，我们cmake一把吧。

[onezeroone@ ex-4]$ cd build/
[onezeroone@ build]$ cmake ..
-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 2.8)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring done
-- Generating done
-- Build files have been written to: /home/onezeroone/work/cmake/ex-4/build
[onezeroone@ build]$ make
Scanning dependencies of target hello
[100%] Building C object lib/CMakeFiles/hello.dir/hello.o
Linking C static library libhello.a
[100%] Built target hello
[onezeroone@ build]$ ls ./lib/
CMakeFiles  cmake_install.cmake  libhello.a  Makefile

呵呵，看到我们的静态库了。

4：安装静态库
   安装前我们要制定安装路径，所以我们再重新构建吧。

[onezeroone@ build]$ cmake -DCMAKE_INSTALL_PREFIX=/usr ..
CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 2.8)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring done
-- Generating done
-- Build files have been written to: /home/onezeroone/work/cmake/ex-4/build
[onezeroone@ build]$ make
[100%] Built target hello
[onezeroone@ build]$ sudo make install
[100%] Built target hello
Install the project...
-- Install configuration: ""
-- Installing: /usr/lib/libhello.a
-- Up-to-date: /usr/include/hello/hello.h

我们可以看到已经安装到指定的/usr目录下面了。

5：使用静态库
   我们修改工程目录下的CMakeLists.txt文件

[onezeroone@ ex-4]$ cat CMakeLists.txt
PROJECT(EX-4)
ADD_SUBDIRECTORY(src bin)

修改库路径为主程序路径，并指定生成bin文件路径。

[onezeroone@ src]$ cat CMakeLists.txt
ADD_EXECUTABLE(main main.c)
INCLUDE_DIRECTORIES(/usr/include/hello)
TARGET_LINK_LIBRARIES(main libhello.a)

指定静态库文件。

再cmake一把把。

[onezeroone@ build]$ cmake ..
CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 2.8)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring done
-- Generating done
-- Build files have been written to: /home/onezeroone/work/cmake/ex-4/build
[onezeroone@ build]$ make
Scanning dependencies of target main
[100%] Building C object bin/CMakeFiles/main.dir/main.o
Linking C executable main
[100%] Built target main
[onezeroone@ build]$ cd bin/
[onezeroone@ bin]$ ls
CMakeFiles  cmake_install.cmake  main  Makefile
[onezeroone@ bin]$ ./main
Hello world

OK我们已经Hello world了，确认下吧。

[onezeroone@ bin]$ ldd main
        linux-gate.so.1 =>  (0x00e09000)
        libc.so.6 => /lib/libc.so.6 (0x00110000)
        /lib/ld-linux.so.2 (0x0078f000)

不再是上一节的动态库了，OK，Done！

6：注
   这里只是简单的实例了cmake构建静态库，后面我们会逐渐丰富。