ROS2笔记2:使用Topic自定义Messages实现nodes之间通讯

1. Package规划1.1 自定义消息接口my_interface_pkgDirCommandRequest.msg请求Topic消息由发起node发起的Topic消息builtin_interfaces/Time stamp # 记录时间戳 string directory # 操作的目录 int8 command # 操作指令. 0:list, 1:rename,2:del string extra_param # 操作指令额外参数DirCommandResult.msg响应Topic消息由响应node回复的Topic消息builtin_interfaces/Time command_stamp # 返回command下发的时间戳 string[] file_names # 目录文件列表 uint32[] file_size_list # 目录文件size列表. 必须与file_names列表一样大小接口命名必须遵守驼峰命名,也就是大写开头单词连接在一起Word1Word2.Colcon build生成代码时会自动将驼峰命名变成Linux风格的’_连接的命名:word1_word2.1.2 请求发起方jack_commander_pkgm_publisher this-create_publishermy_interface_pkg::msg::DirCommandRequest(jack_commander/dir_command_request, 10); m_subscription this-create_subscriptionmy_interface_pkg::msg::DirCommandResult(jack_worker/dir_command_result, 10, std::bind(JackCommanderNode::result_callback, this, std::placeholders::_1));发布jack_commander/dir_command_request话题,使用DirCommandRequest.msg自定义消息订阅jack_worker/dir_command_result话题,使用DirCommandResult.msg自定义消息1.3 请求响应方jack_worker_pkgm_subscription this-create_subscriptionmy_interface_pkg::msg::DirCommandRequest( jack_commander/dir_command_request, 10, std::bind(JackWorkerNode::callback, this, std::placeholders::_1)); m_publisher this-create_publishermy_interface_pkg::msg::DirCommandResult(jack_worker/dir_command_result, 10);发布jack_worker/dir_command_result话题,使用DirCommandResult.msg自定义消息订阅jack_commander/dir_command_request话题,使用DirCommandRequest.msg自定义消息2. 项目目录结构创建ros2包:# 创建自定义消息包ros2 pkg create my_interface_pkg --build-type ament_cmake--licenseApache-2.0--dependenciesbuiltin_interfaces rosidl_default_generators# 创建通讯发起Node包ros2 pkg create jack_commander_pkg --build-type ament_cmake--licenseApache-2.0--dependenciesbuiltin_interfaces my_interface_pkg# 创建通讯响应Node包ros2 pkg create jack_worker_pkg --build-type ament_cmake--licenseApache-2.0--dependenciesbuiltin_interfaces my_interface_pkg创建包后目录结构:jackgaoJackGaoSuper:~/communication$ tree.└── src ├── jack_commander_pkg │ ├── CMakeLists.txt │ ├── LICENSE │ ├── include │ │ └── jack_pub_node │ ├── package.xml │ └── src │ └── jack_commander_node.cpp# 见代码实现添加├── jack_worker_pkg │ ├── CMakeLists.txt │ ├── LICENSE │ ├── include │ │ └── jack_sub_node │ ├── package.xml │ └── src │ ├── jack_worker_node.cpp# 见代码实现添加│ ├── walk_dir.cpp# 见代码实现添加│ └── walk_dir.h# 见代码实现添加└── my_interface_pkg ├── CMakeLists.txt ├── LICENSE ├── README.MD ├── msg │ ├── DirCommandRequest.msg# 见1.1 自定义消息接口│ └── DirCommandResult.msg# 见1.1 自定义消息接口└── package.xml3. 代码实现3.1 自定义消息接口在my_interface_pkg修改CMakeLists.txt添加# find dependencies find_package(ament_cmake REQUIRED) find_package(builtin_interfaces REQUIRED) find_package(rosidl_default_generators REQUIRED) # cmake函数来自rosidl_default_generators,用于将msg接口定义文件转换为C/Python代码 rosidl_generate_interfaces(${PROJECT_NAME} msg/DirCommandRequest.msg msg/DirCommandResult.msg DEPENDENCIES builtin_interfaces )3.2 请求发起方jack_commander_node.cpp#include iostream #include functional #include chrono #include thread #include rclcpp/rclcpp.hpp #include builtin_interfaces/msg/time.hpp #include my_interface_pkg/msg/dir_command_request.hpp #include my_interface_pkg/msg/dir_command_result.hpp using namespace std::chrono_literals; class JackCommanderNode : public rclcpp::Node { public: explicit JackCommanderNode(const std::string node_name,int period_ms) :Node(node_name) { m_period_ms period_ms; m_timer nullptr; m_publisher this-create_publishermy_interface_pkg::msg::DirCommandRequest(jack_commander/dir_command_request, 10); m_subscription this-create_subscriptionmy_interface_pkg::msg::DirCommandResult(jack_worker/dir_command_result, 10, std::bind(JackCommanderNode::result_callback, this, std::placeholders::_1)); } void Set_Param(const std::string dir,ushort cmd,const std::string extra_param) { m_directory dir; m_command cmd; m_extra_param extra_param; RCLCPP_INFO(this-get_logger(),Set_Param: %s, %d, %s,m_directory.c_str(),m_command,m_extra_param.c_str()); if(m_timer) { m_timer-cancel(); m_timer nullptr; } m_timer this-create_wall_timer(std::chrono::milliseconds(static_castint(m_period_ms)),std::bind(JackCommanderNode::timer_callback,this)); } private: std::string m_directory /home/jackgao; ushort m_command0; std::string m_extra_param; double m_period_ms; rclcpp::Time m_last_call_time; rclcpp::TimerBase::SharedPtr m_timer; rclcpp::Publishermy_interface_pkg::msg::DirCommandRequest::SharedPtr m_publisher; rclcpp::Subscriptionmy_interface_pkg::msg::DirCommandResult::SharedPtr m_subscription; void timer_callback() { my_interface_pkg::msg::DirCommandRequest msg; m_last_call_time this-get_clock()-now(); msg.stamp m_last_call_time; msg.directory m_directory; msg.command m_command; msg.extra_param m_extra_param; RCLCPP_INFO(this-get_logger(),Sending command...); RCLCPP_INFO(this-get_logger(),msg.directory:%s,msg.directory.c_str()); RCLCPP_INFO(this-get_logger(),msg.command:%d,msg.command); RCLCPP_INFO(this-get_logger(),msg.extra_param:%s,msg.extra_param.c_str()); m_publisher-publish(msg); } void result_callback(const my_interface_pkg::msg::DirCommandResult::SharedPtr msg) { rclcpp::Time time_from_worker msg-command_stamp; // 本地Request匹配Worker的Result if(time_from_worker m_last_call_time) { RCLCPP_INFO(this-get_logger(),result_callback: %ld,msg-file_names.size()); for(unsigned long i 0;imsg-file_names.size();i) { RCLCPP_INFO(this-get_logger(),#%ld: %s, %d,i,msg-file_names[i].c_str(),msg-file_size_list[i]); } if(m_timer) { m_timer-cancel(); m_timer nullptr; } } } }; // 键盘输入线程函数 void keyboard_input_thread(std::shared_ptrJackCommanderNode node) { while(rclcpp::ok()) { std::string dir; std::cout 请输入查看目录: ; std::cin dir; if(dir exit || dir quit) { std::cout Quitting... std::endl; rclcpp::shutdown(); break; } node-Set_Param(dir,0,); } } int main(int argc, char * argv[]) { rclcpp::init(argc, argv); auto node std::make_sharedJackCommanderNode(jack_commander_node,100); // 创建键盘输入线程 std::thread input_thread(keyboard_input_thread,node); // 在主线程中运行ROS2节点 RCLCPP_INFO(node-get_logger(),Commander: %s is running...,node-get_name()); rclcpp::spin(node); // 等待输入线程结束 if (input_thread.joinable()) { input_thread.join(); } rclcpp::shutdown(); return 0; }头文件中include按如下规律映射:Message接口builtin_interfaces/msg/Time映射为builtin_interfaces/msg/time.hpp.最后的类型必须是驼峰命名(首字母大写单词连接)变成.hpp时驼峰命名全部变成小写单词之间使用_连接。所以my_interface_pkg/msg/DirCommandRequest映射为my_interface_pkg/msg/dir_command_request.hpp;my_interface_pkg/msg/DirCommandResult映射为my_interface_pkg/msg/dir_command_result.hpp.修改CMakeLists.txt添加# find dependencies find_package(rclcpp REQUIRED) find_package(builtin_interfaces REQUIRED) find_package(my_interface_pkg REQUIRED) # 添加可执行文件 add_executable(jack_commander_node src/jack_commander_node.cpp) ament_target_dependencies(jack_commander_node rclcpp builtin_interfaces my_interface_pkg) # 安装可执行文件 install(TARGETS jack_commander_node DESTINATION lib/${PROJECT_NAME})3.3 请求响应方jack_worker_node.cpp#include iostream #include functional #include chrono #include rclcpp/rclcpp.hpp #include builtin_interfaces/msg/time.hpp #include my_interface_pkg/msg/dir_command_request.hpp #include my_interface_pkg/msg/dir_command_result.hpp #include walk_dir.h using namespace std::chrono_literals; class JackWorkerNode : public rclcpp::Node { public: explicit JackWorkerNode(const std::string node_name) : Node(node_name) { m_subscription this-create_subscriptionmy_interface_pkg::msg::DirCommandRequest( jack_commander/dir_command_request, 10, std::bind(JackWorkerNode::callback, this, std::placeholders::_1)); m_publisher this-create_publishermy_interface_pkg::msg::DirCommandResult(jack_worker/dir_command_result, 10); } private: rclcpp::Subscriptionmy_interface_pkg::msg::DirCommandRequest::SharedPtr m_subscription; rclcpp::Publishermy_interface_pkg::msg::DirCommandResult::SharedPtr m_publisher; void callback(const my_interface_pkg::msg::DirCommandRequest::SharedPtr msg) { RCLCPP_INFO(this-get_logger(),Received request: stamp %d.%09d,msg-stamp.sec,msg-stamp.nanosec); RCLCPP_INFO(this-get_logger(),Received request: command %d,msg-command); RCLCPP_INFO(this-get_logger(),Received request: extra_param %s,msg-extra_param.c_str()); RCLCPP_INFO(this-get_logger(),Received request: directory %s,msg-directory.c_str()); auto fileList walkDirectory(msg-directory); RCLCPP_INFO(this-get_logger(),--------------result of directory walk--------------); RCLCPP_INFO(this-get_logger(),Total files: %ld, fileList.size()); my_interface_pkg::msg::DirCommandResult result; result.command_stamp msg-stamp; for(auto file : fileList) { RCLCPP_INFO(this-get_logger(),File: %s, Size: %s, file.filename.c_str(), file.getFormattedSize().c_str()); result.file_names.push_back(file.filename); result.file_size_list.push_back(file.file_size); } m_publisher-publish(result); } }; int main(int argc, char * argv[]) { rclcpp::init(argc, argv); auto node std::make_sharedJackWorkerNode(jack_worker_node); RCLCPP_INFO(node-get_logger(),Worker %s is running...,node-get_name()); rclcpp::spin(node); rclcpp::shutdown(); return 0; }修改CMakeLists.txt添加find_package(rclcpp REQUIRED) find_package(builtin_interfaces REQUIRED) find_package(my_interface_pkg REQUIRED) # 添加可执行文件 add_executable(jack_worker_node src/jack_worker_node.cpp src/walk_dir.cpp) ament_target_dependencies(jack_worker_node rclcpp builtin_interfaces my_interface_pkg) # 安装可执行文件 install(TARGETS jack_worker_node DESTINATION lib/${PROJECT_NAME})4. 编译执行编译jackgaoJackGaoSuper:~/communication$ colcon build Startingmy_interface_pkg Finishedmy_interface_pkg[0.26s]Startingjack_commander_pkg Startingjack_worker_pkg Finishedjack_commander_pkg[5.37s]Finishedjack_worker_pkg[5.38s]Summary:3packages finished[5.80s]编译成功后目录结构如下jackgaoJackGaoSuper:~/communication$ tree-d-L2.├── build │ ├── jack_commander_pkg │ ├── jack_worker_pkg │ └── my_interface_pkg ├──install│ ├── jack_commander_pkg │ ├── jack_worker_pkg │ └── my_interface_pkg ├── log │ ├── build_2026-04-19_09-41-43 │ ├── latest -latest_build │ └── latest_build -build_2026-04-19_09-41-43 └── src ├── jack_commander_pkg ├── jack_worker_pkg └── my_interface_pkg运行终端1运行worker nodesource./install/setup.sh ros2 run jack_worker_pkg jack_worker_node输出[INFO][1776563477.623617672][jack_worker_node]: Workerjack_worker_nodeis running...表示worker node运行正常终端2运行commander nodesource./install/setup.sh ros2 run jack_commander_pkg jack_commander_node输出[INFO][1776563614.307351198][jack_commander_node]: Commander:jack_commander_nodeis running... 请输入查看目录:表示command node运行正常终端3检查运行情况source./install/setup.sh ros2nodelist ros2 topic list ros2nodeinfo /jack_commander_node ros2nodeinfo /jack_commander_node