ROS2 如何实现发布者和订阅者

1、创建工作空间

ros2_workspace cd qhr_ws/src    

ros2 pkg create test_moudle --build-type ament_cmake --dependencies rclcpp

目录格式如上图

2、创建订阅者和发布者code

创建发布者节点

在路径：/qhr_ws/src/test_moudle/src 下创建

 talker.cpp 的文件，内容如下：

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

using namespace std::chrono_literals;

class Talker : public rclcpp::Node {
public:
    Talker() : Node("talker") {
        publisher_ = this->create_publisher<std_msgs::msg::String>("topic", 10);
        auto publish_msg = [this]() -> void {
            auto message = std_msgs::msg::String();
            message.data = "Hello, world! " + std::to_string(count_++);
            RCLCPP_INFO(this->get_logger(), "Publishing: '%s'", message.data.c_str());
            this->publisher_->publish(message);
        };
        timer_ = this->create_wall_timer(500ms, publish_msg);
    }

private:
    rclcpp::TimerBase::SharedPtr timer_;
    rclcpp::Publisher<std_msgs::msg::String>::SharedPtr publisher_;
    size_t count_ = 1;
};

int main(int argc, char * argv[]) {
    rclcpp::init(argc, argv);
    rclcpp::spin(std::make_shared<Talker>());
    rclcpp::shutdown();
    return 0;
}

创建订阅者节点

在同一路径下，创建一个名为 listener.cpp 的文件，内容如下：

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

class Listener : public rclcpp::Node
{
public:
    Listener() : Node("listener")
    {
        subscription_ = this->create_subscription<std_msgs::msg::String>("topic", 10, std::bind(&Listener::topic_callback, this, std::placeholders::_1));
    }

private:
    void topic_callback(const std_msgs::msg::String::SharedPtr msg) const
    {
        RCLCPP_INFO(this->get_logger(), "I heard: '%s'", msg->data.c_str());
    }
    rclcpp::Subscription<std_msgs::msg::String>::SharedPtr subscription_;
};

int main(int argc, char* argv[])
{
    rclcpp::init(argc, argv);
    rclcpp::spin(std::make_shared<Listener>());
    rclcpp::shutdown();
    return 0;
}

3、修改依赖

package.xml文件确保有：

  <buildtool_depend>ament_cmake</buildtool_depend>

  <depend>rclcpp</depend>
  <depend>std_msgs</depend>

CMakeLists.txt

find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)


add_executable(talker src/talker.cpp)
ament_target_dependencies(talker rclcpp std_msgs)

add_executable(listener src/listener.cpp)
ament_target_dependencies(listener rclcpp std_msgs)

install(TARGETS
  talker listener
  DESTINATION lib/${PROJECT_NAME})

4、编译执行

qhr_ws 工作空间下执行

colcon build

编译成功后，开两个终端执行

source install/setup.zsh  (zsh)
source install/setup.bash (bash)

#发布者
ros2 run test_moudle talker

#订阅者
ros2 run test_moudle listener

结束 再次撒花