定义msg文件
//在文件夹learning_topic中新建一个命名为msg的文件夹,存放消息类文件,方便管理
//创建.msg文件 touch Person.msg
//打开该文件,输入以下信息后保存
string name
uint8 sex
uint8 age
uint8 unknown = 0
uint8 male = 1
uint8 female = 2
//这里写的并不是cpp,也不是python。但他在编译过程中会由ros自动编译成cpp或python
在package.xml中添加功能包依赖
//打开文件夹learning_topic,打开package.xml
//gedit package.xml
//保存到最下方/<build_depend>类中
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>
//<build_depend>用于添加编译依赖,这里添加message_generation功能包
//<exec_depend<用于添加执行依赖,这里添加message_runtime功能包
在CMakeLists.txt添加编译选项
//打开文件夹learning_topic,打开CMakeLists.txt。
//在最上方的find_package中添加以下语句
message_generation
//找到Declare ROS dynamic reconfigure parameters的位置,在上方添加以下语句
add_message_files(FILES Person.msg)
generate_messages(DEPENDENCIES std_msgs)
//第一句,告诉编译器Person.msg是我们定义的消息接口
//第二句,告诉编译器在编译Person.msg文件的时候,需要依赖ROS哪些已有的库或者包。
//找到catkin specific configuration(即Build上方),添加以下语句
CATKIN_DEPENDS geometry_msgs roscpp rospy std_msgs turtlesim message_runtime
编译生成语言相关文件
//回到工作空间的根目录catkin_ws下,打开命令行,尝试进行编译。输入指令
catkin_make
创建publisher和subscriber
//person_publisher.cpp
/**
* 该例程将发布/person_info话题,自定义消息类型learning_topic::Person
*/
#include <ros/ros.h>
//!!!!!关键!!!!!
#include "learning_topic/Person.h"
int main(int argc, char **argv)
{
// ROS节点初始化
ros::init(argc, argv, "person_publisher");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个Publisher,发布名为/person_info的topic,消息类型为learning_topic::Person,队列长度10
//!!!!!关键!!!!!
ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);
// 设置循环的频率
ros::Rate loop_rate(1);
int count = 0;
while (ros::ok())
{
// 初始化learning_topic::Person类型的消息
learning_topic::Person person_msg;
person_msg.name = "Tom";
person_msg.age = 18;
person_msg.sex = learning_topic::Person::male;
// 发布消息
person_info_pub.publish(person_msg);
ROS_INFO("Publish Person Info: name:%s age:%d sex:%d",
person_msg.name.c_str(), person_msg.age, person_msg.sex);
// 按照循环频率延时
loop_rate.sleep();
}
return 0;
}
//person_subscriber.cpp
/**
* 该例程将订阅/person_info话题,自定义消息类型learning_topic::Person
*/
#include <ros/ros.h>
//!!!!!关键!!!!!
#include "learning_topic/Person.h"
// 接收到订阅的消息后,会进入消息回调函数
void personInfoCallback(const learning_topic::Person::ConstPtr& msg)
{
// 将接收到的消息打印出来
ROS_INFO("Subcribe Person Info: name:%s age:%d sex:%d",
msg->name.c_str(), msg->age, msg->sex);
}
int main(int argc, char **argv)
{
// 初始化ROS节点
ros::init(argc, argv, "person_subscriber");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个Subscriber,订阅名为/person_info的topic,注册回调函数personInfoCallback
//!!!!!关键!!!!!
ros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);
// 循环等待回调函数
ros::spin();
return 0;
}
配置CMakeLists.txt中的编译规则
*设置需要编译的代码和生成的可执行文件;
*设置链接库;
*添加依赖项.
//这里相比之前配置CMakeLists.txt,多了add_dependencies的语句目的是让可执行文件(前两句做的工作)和动态生成的文件产生依赖关系
//位置依旧,找到Install位置的上方,添加以下语句,保存.
add_executable(person_publisher src/person_publisher.cpp)
target_link_libraries(person_publisher ${catkin_LIBRARIES})
add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)
add_executable(person_subscriber src/person_subscriber.cpp)
target_link_libraries(person_subscriber ${catkin_LIBRARIES})
add_dependencies(person_subscriber ${PROJECT_NAME}_generate_messages_cpp)
编译并运行publisher和subscriber
cd ~/catkin_ws
catkin_make
source devel/setup.bash
roscore
//新开一个终端,运行subscriber
rosrun learning_topic person_subscriber
//新开一个终端,运行publisher
rosrun learning_topic person_publisher
//ROS Master是帮助节点的创建和链接的。节点一旦创建和链接后,就不受ROS Master影响
publisher和subscriber(python)
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 该例程将发布/person_info话题,自定义消息类型learning_topic::Person
import rospy
from learning_topic.msg import Person
def velocity_publisher():
# ROS节点初始化
rospy.init_node('person_publisher', anonymous=True)
# 创建一个Publisher,发布名为/person_info的topic,消息类型为learning_topic::Person,队列长度10
person_info_pub = rospy.Publisher('/person_info', Person, queue_size=10)
#设置循环的频率
rate = rospy.Rate(10)
while not rospy.is_shutdown():
# 初始化learning_topic::Person类型的消息
person_msg = Person()
person_msg.name = "Tom";
person_msg.age = 18;
person_msg.sex = Person.male;
# 发布消息
person_info_pub.publish(person_msg)
rospy.loginfo("Publsh person message[%s, %d, %d]",
person_msg.name, person_msg.age, person_msg.sex)
# 按照循环频率延时
rate.sleep()
if __name__ == '__main__':
try:
velocity_publisher()
except rospy.ROSInterruptException:
pass
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 该例程将订阅/person_info话题,自定义消息类型learning_topic::Person
import rospy
from learning_topic.msg import Person
def personInfoCallback(msg):
rospy.loginfo("Subcribe Person Info: name:%s age:%d sex:%d",
msg.name, msg.age, msg.sex)
def person_subscriber():
# ROS节点初始化
rospy.init_node('person_subscriber', anonymous=True)
# 创建一个Subscriber,订阅名为/person_info的topic,注册回调函数personInfoCallback
rospy.Subscriber("/person_info", Person, personInfoCallback)
# 循环等待回调函数
rospy.spin()
if __name__ == '__main__':
person_subscriber()
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