c++ asio: line-based echo server_boost recv streambuf-优快云博客

本文链接：https://blog.youkuaiyun.com/EricYeung/article/details/4047341

本文介绍如何使用 Boost.Asio 库实现一个简单的聊天服务器。该服务器能够接收客户端发送的消息，并将消息回传给客户端。文章展示了关键代码片段，包括会话类和服务器类的设计，以及异步读写操作的实现。

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#include "stdafx.h"
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <string>

using namespace std;
using boost::asio::ip::tcp;

class session
{
public:
    session(boost::asio::io_service& ios): m_socket(ios)
    {

    }

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

    void start()
    {
        boost::asio::async_read_until(m_socket, m_recvbuf, "/r/n",
            boost::bind(&session::handle_read, this,
            boost::asio::placeholders::error));
    }

    void handle_read(const boost::system::error_code& err)
    {
        if(!err)
        {
            string msg;
            std::istream recv_stream(&m_recvbuf);
            std::getline(recv_stream, msg);

            std::ostream send_stream(&m_sendbuf);
            send_stream << msg;

            cout << "get: " << msg << endl;

            boost::asio::async_write(m_socket,
                m_sendbuf,
                boost::bind(&session::handle_write, this,
                boost::asio::placeholders::error));
        }
        else
        {
            cout << "read end, close session" << endl;
            delete this;
        }
    }

    void handle_write(const boost::system::error_code& err)
    {
        if(!err)
        {
            boost::asio::async_read_until(m_socket, m_recvbuf, "/r/n",
                boost::bind(&session::handle_read, this,
                boost::asio::placeholders::error));
        }
        else
        {
            delete this;
        }
    }

private:
    tcp::socket m_socket;
    boost::asio::streambuf m_recvbuf;
    boost::asio::streambuf m_sendbuf;
};

//typedef boost::shared_ptr<session> session_ptr;
typedef session* session_ptr;

class server
{
public:
    server(boost::asio::io_service& ios, short port):
    m_ios(ios), m_acceptor(m_ios, tcp::endpoint(tcp::v4(), port))
    {
        cout << "start listen on port: " << port << endl;
        do_accept();
    }

    void do_accept()
    {
        //session *new_session = new session(m_ios);
        session_ptr new_session(new session(m_ios));
        m_acceptor.async_accept(new_session->socket(),
            boost::bind(&server::handle_accept, this, new_session,
            boost::asio::placeholders::error));
    }

    void handle_accept(session_ptr new_session,
        const boost::system::error_code& error)
    {
        if(!error)
        {
            cout << "accept connection ..." << endl;
            new_session->start();
            do_accept();
        }
        else
        {
            delete new_session;
        }
    }

private:
    boost::asio::io_service& m_ios;
    tcp::acceptor m_acceptor;
};

int _tmain(int argc, _TCHAR* argv[])
{
    boost::asio::io_service ios;
    server line_svr(ios, 12345);
    ios.run();

    return 0;
}