ros2话题之rclcpp实现的运行测试报错

1362377531

Starting >>> example_topic_rclcpp
--- stderr: example_topic_rclcpp
Error parsing '/home/tzx/d2lros2/chapt3/chapt3_ws/src/example_topic_rclcpp/package.xml':
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/catkin_pkg/package.py", line 610, in parse_package_string
root = dom.parseString(data)
File "/usr/lib/python3.10/xml/dom/minidom.py", line 2000, in parseString
return expatbuilder.parseString(string)
File "/usr/lib/python3.10/xml/dom/expatbuilder.py", line 925, in parseString
return builder.parseString(string)
File "/usr/lib/python3.10/xml/dom/expatbuilder.py", line 223, in parseString
parser.Parse(string, True)
xml.parsers.expat.ExpatError: junk after document element: line 21, column 2

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/opt/ros/humble/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py", line 150, in <module>
main()
File "/opt/ros/humble/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py", line 53, in main
raise e
File "/opt/ros/humble/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py", line 49, in main
package = parse_package_string(
File "/usr/lib/python3/dist-packages/catkin_pkg/package.py", line 612, in parse_package_string
raise InvalidPackage('The manifest contains invalid XML:\n%s' % ex, filename)
catkin_pkg.package.InvalidPackage: Error(s) in package '/home/tzx/d2lros2/chapt3/chapt3_ws/src/example_topic_rclcpp/package.xml':
The manifest contains invalid XML:
junk after document element: line 21, column 2
CMake Error at /opt/ros/humble/share/ament_cmake_core/cmake/core/ament_package_xml.cmake:95 (message):
execute_process(/usr/bin/python3
/opt/ros/humble/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py
/home/tzx/d2lros2/chapt3/chapt3_ws/src/example_topic_rclcpp/package.xml
/home/tzx/d2lros2/chapt3/chapt3_ws/build/example_topic_rclcpp/ament_cmake_core/package.cmake)
returned error code 1
Call Stack (most recent call first):
/opt/ros/humble/share/ament_cmake_core/cmake/core/ament_package_xml.cmake:49 (_ament_package_xml)
/opt/ros/humble/share/ament_lint_auto/cmake/ament_lint_auto_find_test_dependencies.cmake:31 (ament_package_xml)
CMakeLists.txt:21 (ament_lint_auto_find_test_dependencies)

gmake: *** [Makefile:267：cmake_check_build_system] 错误 1

Failed <<< example_topic_rclcpp [1.13s, exited with code 2]

Summary: 0 packages finished [1.62s]
1 package failed: example_topic_rclcpp
1 package had stderr output: example_topic_rclcpp
以上这是运行报错内容cmake_minimum_required(VERSION 3.8)
project(example_topic_rclcpp)

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
add_compile_options(-Wall -Wextra -Wpedantic)
endif()

find dependencies

find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)

if(BUILD_TESTING)
find_package(ament_lint_auto REQUIRED)

the following line skips the linter which checks for copyrights

comment the line when a copyright and license is added to all source files

set(ament_cmake_copyright_FOUND TRUE)

the following line skips cpplint (only works in a git repo)

comment the line when this package is in a git repo and when

a copyright and license is added to all source files

set(ament_cmake_cpplint_FOUND TRUE)
ament_lint_auto_find_test_dependencies()
endif()

ament_package()
add_executable(topic_publisher_01 src/topic_publisher_01.cpp)
ament_target_dependencies(topic_publisher_01 rclcpp)

install(TARGETS
topic_publisher_01
DESTINATION lib/${PROJECT_NAME}
)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)

add_executable(topic_publisher_01 src/topic_publisher_01.cpp)
ament_target_dependencies(topic_publisher_01 rclcpp std_msgs)
以上这是cmakelist内容
<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
<name>example_topic_rclcpp</name>
<version>0.0.0</version>
<description>TODO: Package description</description>
<maintainer email="tzx@todo.todo">tzx</maintainer>
<license>TODO: License declaration</license>

<buildtool_depend>ament_cmake</buildtool_depend>

<depend>rclcpp</depend>

<test_depend>ament_lint_auto</test_depend>
<test_depend>ament_lint_common</test_depend>

<export>
<build_type>ament_cmake</build_type>
</export>
</package>
<buildtool_depend>ament_cmake</buildtool_depend>

<depend>rclcpp</depend>
<depend>std_msgs</depend>

<test_depend>ament_lint_auto</test_depend>
<test_depend>ament_lint_common</test_depend>
以上是package文件内容
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

class TopicPublisher01 : public rclcpp::Node
{
public:
// 构造函数,有一个参数为节点名称
TopicPublisher01(std::string name) : Node(name)
{
RCLCPP_INFO(this->get_logger(), "大家好，我是%s.", name.c_str());
// 创建发布者
command_publisher_ = this->create_publisher<std_msgs::msg::String>("command", 10);
// 创建定时器，500ms为周期，定时发布
timer_ = this->create_wall_timer(std::chrono::milliseconds(500), std::bind(&TopicPublisher01::timer_callback, this));
}

private:
void timer_callback()
{
// 创建消息
std_msgs::msg::String message;
message.data = "forward";
// 日志打印
RCLCPP_INFO(this->get_logger(), "Publishing: '%s'", message.data.c_str());
// 发布消息
command_publisher_->publish(message);
}
// 声名定时器指针
rclcpp::TimerBase::SharedPtr timer_;
// 声明话题发布者指针
rclcpp::Publisher<std_msgs::msg::String>::SharedPtr command_publisher_;
};
int main(int argc,char **argv)
{
rclcpp::init(argc,argv);
auto node=std::make_shared<TopicPublisher01>("topic_publisher_01");
rclcpp::spin(node);
rclcpp::shutdown();
return 0;
}
以上是主程序内容

机器人小伊

从您提供的错误信息和文件内容来看，主要问题在于package.xml文件中有重复的依赖声明，并且这些重复的声明位于文件末尾，这导致了XML解析错误。此外，您的CMakeLists.txt文件中有一些不必要的重复内容，这可能会导致构建过程中的混淆。

解决`package.xml`问题

您的package.xml文件中，<buildtool_depend>, <depend>, 和 <test_depend> 标签被重复了。您应该只在文件中声明一次这些依赖。修改后的package.xml应该如下所示：

<?xml version="1.0"?>
<package format="3">
  <name>example_topic_rclcpp</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="tzx@todo.todo">tzx</maintainer>
  <license>TODO: License declaration</license>

  <buildtool_depend>ament_cmake</buildtool_depend>

  <depend>rclcpp</depend>
  <depend>std_msgs</depend>

  <test_depend>ament_lint_auto</test_depend>
  <test_depend>ament_lint_common</test_depend>

  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>

解决`CMakeLists.txt`问题

在CMakeLists.txt中，您重复了find_package和add_executable的调用。此外，std_msgs的find_package应该在创建发布者之前调用。修改后的CMakeLists.txt应该如下所示：

cmake_minimum_required(VERSION 3.8)
project(example_topic_rclcpp)

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  add_compile_options(-Wall -Wextra -Wpedantic)
endif()

find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)  # 确保在创建发布者之前找到std_msgs

if(BUILD_TESTING)
  find_package(ament_lint_auto REQUIRED)
  # 跳过版权和linter检查的设置（仅当实际添加版权和版权文件时取消注释）
  # set(ament_cmake_copyright_FOUND TRUE)
  # set(ament_cmake_cpplint_FOUND TRUE)
  ament_lint_auto_find_test_dependencies()
endif()

ament_package()

add_executable(topic_publisher_01 src/topic_publisher_01.cpp)
ament_target_dependencies(topic_publisher_01 rclcpp std_msgs)

install(TARGETS
  topic_publisher_01
  DESTINATION lib/${PROJECT_NAME}
)

其他建议

确保在package.xml和CMakeLists.txt中添加了必要的许可证和描述信息。
在代码中添加适当的注释和文档，以提高可读性和可维护性。
如果可能的话，使用版本控制系统（如Git）来管理您的ROS 2项目。

完成这些修改后，您应该能够成功构建和运行您的ROS 2节点。

以上为生成回答，仅供参考～

小鱼

@1362377531 如果是学习ROS2，请换到最新的教程和书籍：https://www.bilibili.com/video/BV1GW42197Ck/ 上来，之前的动手学ROS2相关教程停止答疑，经历有限，只能维护一份，还请理解。