《动手学ROS2》5.8Action客户端Python实现

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5.8 Action客户端Python实现

因为后续课程使用到Action的地方都是在最后阶段，为了减轻大家学习负担，先不进行讲解，有兴趣的同学可以参考官方例程源码，小鱼这里也贴一份放在这。

from action_msgs.msg import GoalStatus
from example_interfaces.action import Fibonacci

import rclpy
from rclpy.action import ActionClient
from rclpy.node import Node


class MinimalActionClient(Node):

    def __init__(self):
        super().__init__('minimal_action_client')
        self._action_client = ActionClient(self, Fibonacci, 'fibonacci')

    def goal_response_callback(self, future):
        goal_handle = future.result()
        if not goal_handle.accepted:
            self.get_logger().info('Goal rejected :(')
            return

        self.get_logger().info('Goal accepted :)')

        self._get_result_future = goal_handle.get_result_async()
        self._get_result_future.add_done_callback(self.get_result_callback)

    def feedback_callback(self, feedback):
        self.get_logger().info('Received feedback: {0}'.format(feedback.feedback.sequence))

    def get_result_callback(self, future):
        result = future.result().result
        status = future.result().status
        if status == GoalStatus.STATUS_SUCCEEDED:
            self.get_logger().info('Goal succeeded! Result: {0}'.format(result.sequence))
        else:
            self.get_logger().info('Goal failed with status: {0}'.format(status))

        # Shutdown after receiving a result
        rclpy.shutdown()

    def send_goal(self):
        self.get_logger().info('Waiting for action server...')
        self._action_client.wait_for_server()

        goal_msg = Fibonacci.Goal()
        goal_msg.order = 10

        self.get_logger().info('Sending goal request...')

        self._send_goal_future = self._action_client.send_goal_async(
            goal_msg,
            feedback_callback=self.feedback_callback)

        self._send_goal_future.add_done_callback(self.goal_response_callback)


def main(args=None):
    rclpy.init(args=args)

    action_client = MinimalActionClient()

    action_client.send_goal()

    rclpy.spin(action_client)


if __name__ == '__main__':
    main()

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