参数的用法——利用参数创建节点 ROS 消息通讯——服务器/客户端的来龙去脉

在 ROS 消息通讯——服务器/客户端的来龙去脉的基础上，对service_server.cpp文件进行修改如下：

 1 #include <ros/ros.h>
 2 #include <ros_tutorials_service/SrvTutorial.h>//服务头文件
 3 
 4 #define PLUS 1
 5 #define MINUS 2
 6 #define MULTIPLICATION 3
 7 #define DIVISION 4
 8 
 9 int g_operator=PLUS;
10 //如果收到客户端的请求，将执行以下处理，服务请求为req,服务响应为res
11 bool calculation(ros_tutorials_service::SrvTutorial::Request &req,
12                 ros_tutorials_service::SrvTutorial::Response &res)
13 {
14 //收到请求时，将两数之和保存到服务响应值中
15 switch(g_operator)
16 {
17 case PLUS:
18 res.result = req.a+req.b;break;
19 case MINUS:
20 res.result = req.a-req.b;break;
21 case MULTIPLICATION:
22 res.result = req.a*req.b;break;
23 case DIVISION:
24 if(req.b==0)
25 {
26 res.result =0;break;
27 }
28 else
29 {
30 res.result = req.a/req.b;break;
31 }
32 default:
33 res.result = req.a+req.b;break;
34 //显示a,b的值及结果
35 ROS_INFO("request:x=%ld,y=%ld",(long int)req.a,(long int)req.b);
36 ROS_INFO("sending back response:%ld",(long int)res.result);
37 return true;
38 }
39 
40 int main(int argc,char **argv)
41 {
42 ros::init(argc,argv,"service_server");//声明服务器节点名称
43 ros::NodeHandle nh;
44 nh.setParam("calculation_method",PLUS);//初始化设置参数
45 //声明服务器，创建一个使用ros_tutorials_service功能包SrvTutorial服务文件的服务器
46 //ros_tutorial_service_server,服务名称是ros_tutorial_srv,有服务请求，执行calculation函数
47 ros::ServiceServer ros_tutorials_service_server = nh.advertiseService("ros_tutorial_srv", calculation);
48 
49 ROS_INFO("ready srv server!");
50 ros::Rater(10);
51 while(1)
52 {
53 nh.getParam("calculation_method",g_operator);//获取参数
54 ros::spinOnce();
55 r.sleep();
56 }
57 
58 return 0;
59 }

• 运行结果对照：查看参数列表，修改参数试验效果

•  有参数运行实例：git clone https://github.com/ROBOTIS-GIT/ros_tutoruals.git