现在有一个ros功能包如何用c/c++代码实现暴露该功能包的http端口使得postman能够测试该功能包,接收postman发送的请求，返回ros功能包的返回值 完整代码

你需要在ROS功能包中添加一个HTTP服务器，可以使用开源的库，如Boost.Asio或Poco库。然后，你需要实现一个HTTP请求处理程序，通过HTTP POST请求来调用ROS功能包的服务，并将服务返回值作为HTTP响应发送回客户端。下面是一个示例代码，你可以将其添加到ROS功能包中的C++源文件中：

#include <ros/ros.h>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <string>
#include <sstream>
#include <jsoncpp/json/json.h>

using boost::asio::ip::tcp;

class HttpServer {
public:
  HttpServer(ros::NodeHandle& nh, const std::string& address, int port)
      : nh_(nh), acceptor_(io_service_, tcp::endpoint(boost::asio::ip::address::from_string(address), port)) {
    startAccept();
  }

private:
  ros::NodeHandle nh_;
  boost::asio::io_service io_service_;
  tcp::acceptor acceptor_;

  void startAccept() {
    tcp::socket socket(io_service_);
    acceptor_.async_accept(socket, boost::bind(&HttpServer::handleAccept, this, socket, boost::asio::placeholders::error));
  }

  void handleAccept(tcp::socket& socket, const boost::system::error_code& error) {
    if (!error) {
      boost::asio::streambuf request;
      boost::asio::read_until(socket, request, "\r\n\r\n");

      std::string response_content = handleRequest(request);

      std::stringstream response_stream;
      response_stream << "HTTP/1.1 200 OK\r\n";
      response_stream << "Content-Type: application/json\r\n";
      response_stream << "Content-Length: " << response_content.length() << "\r\n\r\n";
      response_stream << response_content;

      std::string response = response_stream.str();

      boost::asio::write(socket, boost::asio::buffer(response));
    }

    startAccept();
  }

  std::string handleRequest(boost::asio::streambuf& request) {
    std::istream request_stream(&request);

    std::string method;
    request_stream >> method;

    std::string url;
    request_stream >> url;

    std::string http_version;
    request_stream >> http_version;

    std::string header;
    getline(request_stream, header);

    std::string content;
    while (getline(request_stream, content)) {
      if (content.empty()) {
        break;
      }
    }

    if (method != "POST") {
      return "{\"error\": \"Method not supported\"}";
    }

    if (url != "/ros_service") {
      return "{\"error\": \"URL not supported\"}";
    }

    if (content.empty()) {
      return "{\"error\": \"No content in request\"}";
    }

    Json::Value json_request;
    Json::Reader json_reader;
    if (!json_reader.parse(content, json_request)) {
      return "{\"error\": \"Invalid JSON content\"}";
    }

    std::string service_name = json_request["service_name"].asString();
    Json::Value service_request = json_request["service_request"];

    ros::ServiceClient client = nh_.serviceClient<ros::ServiceTypeFromString<service_name> >(service_name);
    ros::ServiceTypeFromString<service_name>::Request req;
    ros::ServiceTypeFromString<service_name>::Response res;
    if (ros::service::call(service_name, req, res)) {
      Json::Value response;
      response["success"] = true;
      response["service_response"] = res;
      return response.toStyledString();
    } else {
      return "{\"error\": \"Service call failed\"}";
    }
  }
};

int main(int argc, char** argv) {
  ros::init(argc, argv, "http_server");

  ros::NodeHandle nh("~");

  std::string server_address;
  int server_port;
  nh.param<std::string>("server_address", server_address, "127.0.0.1");
  nh.param<int>("server_port", server_port, 8080);

  HttpServer http_server(nh, server_address, server_port);

  ros::spin();
  return 0;
}

这个示例代码实现了一个简单的HTTP服务器，监听指定的地址和端口，接受来自客户端的HTTP POST请求，并将请求转换为ROS服务调用，将服务返回值作为JSON格式的HTTP响应发送回客户端。你需要将示例代码中的“ros_service”修改为你要调用的ROS服务名称。