在ROS2 Jazzy中，自定义C++库及其应用需要遵循ROS2的规范，以确保库能够正确编译、安装并被其他包调用。以下是一个详细的范例，包括自定义C++库的创建、编译以及在另一个包中的应用。

一、自定义C++库的创建与编译

1. 创建库包

   • 创建一个新的ROS2工作空间（如果尚未创建）：

   mkdir -p ~/ros2_ws/src
   cd ~/ros2_ws/src
   

   • 创建一个新的包，用于存放自定义库：

   ros2 pkg create --build-type ament_cmake --license Apache-2.0 ros2_cpp_lib
   

   • 进入包目录并创建必要的文件夹结构：

   cd ros2_cpp_lib
   mkdir -p include/ros2_cpp_lib src
   

2. 编写库头文件

   • 在include/ros2_cpp_lib/目录下创建头文件ros2_cpp_lib.hpp：

   #ifndef ROS2_CPP_LIB_HPP
   #define ROS2_CPP_LIB_HPP
   
   #include "rclcpp/rclcpp.hpp"
   
   namespace ros2_cpp_lib {
   
   class ros2_cpp_lib : public rclcpp::Node {
   public:
       ros2_cpp_lib(const std::string& node_name);
       ~ros2_cpp_lib();
       void sum(int a, int b);
   };
   
   } // namespace ros2_cpp_lib
   
   #endif // ROS2_CPP_LIB_HPP
   

3. 编写库源文件

   • 在src/目录下创建源文件ros2_cpp_lib.cpp：

   #include "ros2_cpp_lib/ros2_cpp_lib.hpp"
   
   namespace ros2_cpp_lib {
   
   ros2_cpp_lib::ros2_cpp_lib(const std::string& node_name) : Node(node_name) {
       RCLCPP_INFO(this->get_logger(), "ros2_cpp_lib_node has been started.");
   }
   
   ros2_cpp_lib::~ros2_cpp_lib() {
       RCLCPP_INFO(this->get_logger(), "ros2_cpp_lib_node has been stopped.");
   }
   
   void ros2_cpp_lib::sum(int a, int b) {
       RCLCPP_INFO(this->get_logger(), "Sum of %d and %d is %d", a, b, a + b);
   }
   
   } // namespace ros2_cpp_lib
   

4. 配置CMakeLists.txt

   • 编辑CMakeLists.txt文件，添加以下内容：

   cmake_minimum_required(VERSION 3.8)
   project(ros2_cpp_lib)
   
   if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
       add_compile_options(-Wall -Wextra -Wpedantic)
   endif()
   
   # find dependencies
   find_package(ament_cmake REQUIRED)
   find_package(rclcpp REQUIRED)
   
   # COMPILE
   add_library(ros2_cpp_lib SHARED src/ros2_cpp_lib.cpp)
   target_compile_features(ros2_cpp_lib PUBLIC cxx_std_17)
   target_include_directories(ros2_cpp_lib PUBLIC
       $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
       $<INSTALL_INTERFACE:include/ros2_cpp_lib>
   )
   ament_target_dependencies(ros2_cpp_lib PUBLIC rclcpp)
   
   # EXPORTS
   ament_export_targets(export_ros2_cpp_lib HAS_LIBRARY_TARGET)
   ament_export_dependencies(rclcpp)
   
   # INSTALL
   install(
       DIRECTORY include/ros2_cpp_lib
       DESTINATION include
   )
   install(
       TARGETS ros2_cpp_lib
       EXPORT export_ros2_cpp_lib
       ARCHIVE DESTINATION lib
       LIBRARY DESTINATION lib
       RUNTIME DESTINATION bin
       INCLUDES DESTINATION include
   )
   
   if(BUILD_TESTING)
       find_package(ament_lint_auto REQUIRED)
       set(ament_cmake_uncrustify_FOUND TRUE)
       set(ament_cmake_xmllint_FOUND TRUE)
       ament_lint_auto_find_test_dependencies()
   endif()
   
   ament_package()
   

5. 编译库

   • 返回工作空间根目录并编译：

   cd ~/ros2_ws
   colcon build --packages-up-to ros2_cpp_lib
   

二、在另一个包中应用自定义库

1. 创建应用包

   • 在src/目录下创建一个新的包，用于应用自定义库：

   ros2 pkg create --build-type ament_cmake --license Apache-2.0 ros2_cpp_lib_demos --dependencies rclcpp ros2_cpp_lib
   

2. 编写应用节点

   • 在ros2_cpp_lib_demos/src/目录下创建节点文件demo_node.cpp：

   #include "rclcpp/rclcpp.hpp"
   #include "ros2_cpp_lib/ros2_cpp_lib.hpp"
   
   class DemoNode : public rclcpp::Node {
   public:
       DemoNode() : Node("demo_node") {
           auto lib_node = std::make_shared<ros2_cpp_lib::ros2_cpp_lib>("lib_node");
           lib_node->sum(3, 4);
       }
   };
   
   int main(int argc, char** argv) {
       rclcpp::init(argc, argv);
       rclcpp::spin(std::make_shared<DemoNode>());
       rclcpp::shutdown();
       return 0;
   }
   

3. 配置CMakeLists.txt

   • 编辑ros2_cpp_lib_demos/CMakeLists.txt文件，添加以下内容：

   cmake_minimum_required(VERSION 3.8)
   project(ros2_cpp_lib_demos)
   
   if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
       add_compile_options(-Wall -Wextra -Wpedantic)
   endif()
   
   # find dependencies
   find_package(ament_cmake REQUIRED)
   find_package(rclcpp REQUIRED)
   find_package(ros2_cpp_lib REQUIRED)
   
   # COMPILE
   add_executable(demo_node src/demo_node.cpp)
   target_compile_features(demo_node PUBLIC cxx_std_17)
   ament_target_dependencies(demo_node rclcpp ros2_cpp_lib)
   
   # INSTALL
   install(TARGETS
       demo_node
       DESTINATION lib/${PROJECT_NAME}
   )
   
   if(BUILD_TESTING)
       find_package(ament_lint_auto REQUIRED)
       set(ament_cmake_uncrustify_FOUND TRUE)
       set(ament_cmake_xmllint_FOUND TRUE)
       ament_lint_auto_find_test_dependencies()
   endif()
   
   ament_package()
   

4. 编译并运行应用

   • 返回工作空间根目录并编译：

   cd ~/ros2_ws
   colcon build --packages-up-to ros2_cpp_lib_demos
   

   • 运行应用节点：

   source install/setup.bash
   ros2 run ros2_cpp_lib_demos demo_node