<launch><param name="isLoad" type="bool" value="true"/>       #定义全局标签 bool <node name="yaml" pkg="example_2" type="yaml" clear_params="true" output="screen">#四个相对应的参数<param name="first_name" type="string" value="fabio" /><param name="last_name" type="string" value="miao" /><param name="age" type="int" value="39" /><param name="score" type="int" value="150" /></node>
</launch>

 步骤2：创建配置文件config/test.yaml

first_name: fabio
last_name: miaozl
age: 37
score: 100#注意中间一定需要空格

 步骤4：读取参数，创建yaml.cpp

#include <ros/ros.h>int main(int argc, char **argv)
{ros::init(argc, argv, "yaml");           // 生成yaml的节点ros::NodeHandle nh;                      // std::string first,last;int age = 0 , score = 100;bool isLoad = false;nh.getParam("/yaml/first_name",first);  // 读出节点中的值加入读出nh.getParam("/yaml/last_name",last);ROS_INFO("his first name is %s,his last name is %s",first.c_str(),last.c_str());  nh.getParam("/yaml/age",age);            // 读年龄 读分数ROS_INFO("first name is %d",age);nh.getParam("/yaml/score",score);ROS_INFO("first name is %d",score);nh.getParam("/isLoad",isLoad);if(isLoad){ROS_INFO("the param is load");}else{ROS_INFO("the param isn't load");}
}

 步骤5：修改CMakeLists.txt

主要添加修改文件 ---  编译link Libraries 库文件

cmake_minimum_required(VERSION 3.0.2)
project(example_2)## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTSroscpprospystd_msgsmessage_generationdynamic_reconfigure
)## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()################################################
## Declare ROS messages, services and actions ##
################################################## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)## Generate messages in the 'msg' folder
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )## Generate added messages and services with any dependencies listed here
# generate_messages(
#   DEPENDENCIES
#   std_msgs
# )################################################
## Declare ROS dynamic reconfigure parameters ##
################################################## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed## Generate dynamic reconfigure parameters in the 'cfg' foldergenerate_dynamic_reconfigure_options(cfg/Test.cfg)###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES example_2
#  CATKIN_DEPENDS roscpp rospy std_msgs
#  DEPENDS system_lib
)###########
## Build ##
############# Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include${catkin_INCLUDE_DIRS}
)## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/example_2.cpp
# )## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/example_2_node.cpp)
add_executable(yaml src/yaml.cpp)
add_executable(param src/param.cpp)
## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )
target_link_libraries(yaml${catkin_LIBRARIES}
)
target_link_libraries(param${catkin_LIBRARIES}
)
#############
## Install ##
############## all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# catkin_install_python(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )#############
## Testing ##
############### Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_example_2.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

执行launch后得到

... logging to /home/xtark/.ros/log/deb4219e-2151-11ed-a25f-874955d4690a/roslaunch-xtark-vmpc-6737.log
Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.started roslaunch server http://xtark-vmpc:33649/SUMMARY
========CLEAR PARAMETERS* /yaml/PARAMETERS* /isLoad: True* /rosdistro: noetic* /rosversion: 1.15.13* /yaml/age: 39* /yaml/first_name: fabio* /yaml/last_name: miao* /yaml/score: 150NODES/yaml (example_2/yaml)ROS_MASTER_URI=http://localhost:11311process[yaml-1]: started with pid [6755]
[ INFO] [1661087150.225233609]: his first name is fabio,his last name is miao
[ INFO] [1661087150.226000645]: first name is 39
[ INFO] [1661087150.226231003]: first name is 150
[ INFO] [1661087150.226447102]: the param is load
[yaml-1] process has finished cleanly
log file: /home/xtark/.ros/log/deb4219e-2151-11ed-a25f-874955d4690a/yaml-1*.log
all processes on machine have died, roslaunch will exit
shutting down processing monitor...
... shutting down processing monitor complete
done