Windows 编译 MQTT C

如果遇到报错

ADD_LIBRARY cannot create target "paho-mqtt3c" because another target with   the same name already exists.  The existing target is a shared library   created in source directory

需要更改

..paho.mqtt.csrc

下的CMakeLists.txt，将 -static后缀添加到文件中的静态库名称上，有两个地方需要进行此更改，在该文件中搜索PAHO_BUILD_STATIC：

第94行附近（添加-static到if语句中引用的库名称中）：

IF (PAHO_BUILD_STATIC)
    ADD_LIBRARY(paho-mqtt3c-static STATIC $<TARGET_OBJECTS:common_obj> MQTTClient.c)
    ADD_LIBRARY(paho-mqtt3a-static STATIC $<TARGET_OBJECTS:common_obj> MQTTAsync.c)

    TARGET_LINK_LIBRARIES(paho-mqtt3c-static ${LIBS_SYSTEM})
    TARGET_LINK_LIBRARIES(paho-mqtt3a-static ${LIBS_SYSTEM})

    INSTALL(TARGETS paho-mqtt3c-static paho-mqtt3a-static
    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
ENDIF()

在第164行附近（添加-static到if语句中引用的库名称中）：

IF (PAHO_BUILD_STATIC)
    ADD_LIBRARY(paho-mqtt3cs-static STATIC $<TARGET_OBJECTS:common_ssl_obj> MQTTClient.c SSLSocket.c)
    ADD_LIBRARY(paho-mqtt3as-static STATIC $<TARGET_OBJECTS:common_ssl_obj> MQTTAsync.c SSLSocket.c)

    TARGET_LINK_LIBRARIES(paho-mqtt3cs-static ${OPENSSL_LIBRARIES} ${LIBS_SYSTEM})
    TARGET_LINK_LIBRARIES(paho-mqtt3as-static ${OPENSSL_LIBRARIES} ${LIBS_SYSTEM})
    SET_TARGET_PROPERTIES(
        paho-mqtt3cs-static paho-mqtt3as-static PROPERTIES
        VERSION ${CLIENT_VERSION}
        SOVERSION ${PAHO_VERSION_MAJOR}
    COMPILE_DEFINITIONS "OPENSSL=1")

    INSTALL(TARGETS paho-mqtt3cs-static paho-mqtt3as-static
    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
ENDIF()

进行更改后，清除CMake缓存（或删除构建文件夹中的CMakeCache.txt文件）并重新运行CMake。