c++中http服务，收发json格式数据的例子

以下是一个简单的使用C++编写的HTTP服务器，用于接收并处理JSON格式的请求数据。

#include <iostream>
#include <string>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>

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

class session
{
public:
    session(boost::asio::io_service& io_service)
        : socket_(io_service)
    {
    }

    tcp::socket& socket()
    {
        return socket_;
    }

    void start()
    {
        boost::asio::async_read_until(socket_, request_, "\r\n\r\n",
            boost::bind(&session::handle_read, this,
                boost::asio::placeholders::error,
                boost::asio::placeholders::bytes_transferred));
    }

    void handle_read(const boost::system::error_code& error,
        size_t bytes_transferred)
    {
        if (!error)
        {
            std::istream request_stream(&request_);
            std::string header;
            while (std::getline(request_stream, header) && header != "\r")
            {
                // Handle request headers
            }

            std::stringstream ss;
            ss << request_stream.rdbuf();
            std::string body = ss.str();

            // Parse JSON
            boost::property_tree::ptree pt;
            std::istringstream is(body);
            boost::property_tree::read_json(is, pt);

            // Handle JSON data
            std::string response_data = "Received JSON data:\n" + body;

            // Construct response
            std::string response = "HTTP/1.1 200 OK\r\n";
            response += "Content-Type: text/plain\r\n";
            response += "Content-Length: " + std::to_string(response_data.length()) + "\r\n";
            response += "\r\n";
            response += response_data;

            boost::asio::async_write(socket_, boost::asio::buffer(response),
                boost::bind(&session::handle_write, this,
                    boost::asio::placeholders::error));
        }
        else
        {
            delete this;
        }
    }

    void handle_write(const boost::system::error_code& error)
    {
        if (!error)
        {
            delete this;
        }
    }

private:
    tcp::socket socket_;
    boost::asio::streambuf request_;
};

class server
{
public:
    server(boost::asio::io_service& io_service, short port)
        : io_service_(io_service),
        acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
    {
        start_accept();
    }

private:
    void start_accept()
    {
        session* new_session = new session(io_service_);
        acceptor_.async_accept(new_session->socket(),
            boost::bind(&server::handle_accept, this, new_session,
                boost::asio::placeholders::error));
    }

    void handle_accept(session* new_session,
        const boost::system::error_code& error)
    {
        if (!error)
        {
            new_session->start();
        }
        else
        {
            delete new_session;
        }

        start_accept();
    }

    boost::asio::io_service& io_service_;
    tcp::acceptor acceptor_;
};

int main()
{
    try
    {
        boost::asio::io_service io_service;
        server s(io_service, 8080);
        io_service.run();
    }
    catch (std::exception& e)
    {
        std::cerr << "Exception: " << e.what() << "\n";
    }

    return 0;
}

在上面的代码中，我们使用了`boost::asio`库来处理HTTP请求和响应。`session`类表示一个HTTP会话，它处理一个连接。这个类使用了异步编程方式，使用`boost::asio::async_read_until`函数来读取请求数据，然后使用`boost::property_tree`库解析JSON数据。解析完成后，我们可以处理JSON数据并构造响应。最后，我们使用`boost::asio::async_write`函数将响应发送回客户端。

在`server`类中，我们创建一个`tcp::acceptor`对象来监听指定端口的HTTP连接。当有新连接时，我们使用`async_accept`函数接受连接并创建一个新的`session`对象来处理这个连接。为了支持多个连接，我们在`handle_accept`函数中调用`start_accept`函数来接受下一个连接。

请注意，上面的代码仅仅是一个示例，它没有对请求进行任何验证或者错误处理。在实际应用中，您应该根据您的需求来添加适当的验证和错误处理。