学习视频:https://www.bilibili.com/video/BV1zt411G7Vn?p=13
目标:通过客户端程序发布请求给spawn服务器创建第二只小海龟
一、创建功能包
打开终端,输入命令
cd ~/catkin_ws/src
catkin_create_pkg learning_service roscpp rospy stdmsgs geometry_msgs turtlesim
二、用C++创建客户端代码
1.创建客户端代码
输入指令,打开turtle_spawn.cpp文件
gedit ~/catkin_ws/src/learning_service/src/turtle_spawn.cpp
复制下列代码,保存退出。
/***********************************************************************
Copyright 2020 GuYueHome (www.guyuehome.com).
***********************************************************************/
/**
* 该例程将请求/spawn服务,服务数据类型turtlesim::Spawn
*/
#include <ros/ros.h>
#include <turtlesim/Spawn.h>
int main(int argc, char** argv)
{
// 初始化ROS节点
ros::init(argc, argv, "turtle_spawn");
// 创建节点句柄
ros::NodeHandle node;
// 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的service
ros::service::waitForService("/spawn");
ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("/spawn");
// 初始化turtlesim::Spawn的请求数据
turtlesim::Spawn srv;
srv.request.x = 2.0;
srv.request.y = 2.0;
srv.request.name = "turtle2";
// 请求服务调用
ROS_INFO("Call service to spwan turtle[x:%0.6f, y:%0.6f, name:%s]",
srv.request.x, srv.request.y, srv.request.name.c_str());
add_turtle.call(srv);
// 显示服务调用结果
ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str());
return 0;
};
2.配置客户端代码编译规制
输入指令,打开CMakeList.txr文件
gedit ~/catkin_ws/src/learning_service/CMakeLists.txt
加入下面代码如下图所示
add_executable(turtle_spawn src/turtle_spawn.cpp)
target_link_libraries(turtle_spawn ${catkin_LIBRARIES})
三、用Pyhton创建客户端代码
1.创建客户端代码
输入指令,打开turtle_spawn.py文件。
mkdir ~/catkin_ws/src/learning_service/scripts
gedit ~/catkin_ws/src/learning_service/scripts/turtle_spawn.py
复制下列代码,保存关闭文件。
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
########################################################################
#### Copyright 2020 GuYueHome (www.guyuehome.com). ###
########################################################################
# 该例程将请求/spawn服务,服务数据类型turtlesim::Spawn
import sys
import rospy
from turtlesim.srv import Spawn
def turtle_spawn():
# ROS节点初始化
rospy.init_node('turtle_spawn')
# 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的service
rospy.wait_for_service('/spawn')
try:
add_turtle = rospy.ServiceProxy('/spawn', Spawn)
# 请求服务调用,输入请求数据
response = add_turtle(2.0, 2.0, 0.0, "turtle2")
return response.name
except rospy.ServiceException as e:
print("Service call failed: %s" %e)
if __name__ == "__main__":
#服务调用并显示调用结果
print("Spwan turtle successfully [name:%s]" %(turtle_spawn()))
这里Python3和Python2语法不相同,我作了一些修改。
2.设置turtle_spawn.py 文件运行权限
cd ~/catkin_ws/src/learning_service/scripts
chmod +x turtle_spawn.py
四、编译功能包(Python不需要)
cd ~/catkin_ws/
catkin_make
五、运行程序
1.运行roscore
roscore
2.打开新的终端,运行小海龟仿真器
rosrun turtlesim turtlesim_node
3.打开新的终端,运行指令
rosrun learning_service turtle_spawn.py
4.运行效果如下