boost asio 网络聊天 代码修改学习

#pragma once

#include <cstdio>
#include <cstdlib>
#include <cstring>

class chat_message
{
public:
	enum { header_length = 4 };
	enum { max_body_length = 512 };

	chat_message():
		body_length_(0)
	{}

	const char* data()const
	{
		return data_;
	}

	char* data()
	{
		return data_;
	}

	size_t length()const
	{
		return header_length + body_length_;
	}

	const char* body()const
	{
		return data_ + header_length;
	}
	char* body()
	{
		return data_ + header_length;
	}
	size_t body_length()const
	{
		return body_length_;
	}

	void body_length(size_t new_length)
	{
		body_length_ = new_length;
		if (body_length_ > max_body_length)
			body_length_ = max_body_length;
	}

	bool decode_header()
	{
		using namespace std;
		char header[header_length + 1] = "";
		strncat(header, data_, header_length);
		body_length_ = atoi(header);
		if (body_length_ > max_body_length)
		{
			body_length_ = 0;
			return false;
		}
		return true;
	}

	void encode_header()
	{
		using namespace std;
		char header[header_length + 1] = "";
		sprintf(header,"%4d",static_cast<int>(body_length_));
		memcpy(data_,header,header_length);
	}

private:
	char data_[header_length + max_body_length];
	size_t body_length_;
};

// MyChat.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <boost/asio.hpp>
#include <set>
#include <iostream>
#include "chat_message.h"

using namespace boost::asio::ip;

const int defaultPort = 8899;

class chat_session;
typedef boost::shared_ptr<chat_session> chat_session_ptr;

class chat_session :
public	boost::enable_shared_from_this<chat_session>
{
public:
	chat_session(boost::asio::io_service& io_service, std::set<chat_session_ptr>& sessionList)
		: socket_(io_service), sessionList_(sessionList)
	{
	}

	~chat_session() { std::cout << "~chat_session()" << std::endl; }
	tcp::socket& socket()
	{
		return socket_;
	}

	void start()
	{
		sessionList_.insert(shared_from_this());
		boost::asio::async_read(socket_,
			boost::asio::buffer(read_msg_.data(), chat_message::header_length),
			boost::bind(
				&chat_session::handle_read_header, shared_from_this(),
				boost::asio::placeholders::error));
	}

	void handle_read_header(const boost::system::error_code& error)
	{
		if (!error && read_msg_.decode_header() )
		{
			boost::asio::async_read(socket_,
				boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
				boost::bind(&chat_session::handle_read_body, shared_from_this(),
					boost::asio::placeholders::error));
		}
		else
		{
			// occur error,delete from list
			sessionList_.erase(shared_from_this());
			socket_.shutdown(tcp::socket::shutdown_both);
			socket_.close();
			return;
		}
	}

	void handle_read_body(const boost::system::error_code& error)
	{
		if (!error)
		{
			std::cout << read_msg_.data() << std::endl;
			boost::asio::async_read(socket_,
				boost::asio::buffer(read_msg_.data(), chat_message::header_length),
				boost::bind(&chat_session::handle_read_header, shared_from_this(),
					boost::asio::placeholders::error));
		}
		else
		{
			// occur error,delete from list
			sessionList_.erase(shared_from_this());
			socket_.shutdown(tcp::socket::shutdown_both);
			socket_.close();
			return;
		}

	}



private:
	char recvbuf[5];
	tcp::socket socket_;
	chat_message read_msg_;
	std::set<chat_session_ptr>& sessionList_;
};


typedef boost::shared_ptr<chat_session> chat_session_ptr;

class chat_server
{
public:
	chat_server(boost::asio::io_service& io_service,
		const tcp::endpoint& endpoint)
		: io_service_(io_service),
		acceptor_(io_service, endpoint)
	{
		start_accept();
	}

	void start_accept()
	{
		chat_session_ptr new_session(new chat_session(io_service_, sessionList_));
		acceptor_.async_accept(new_session->socket(),
			boost::bind(&chat_server::handle_accept, this, new_session,
				boost::asio::placeholders::error));
	}

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

		start_accept();
	}
private:
	boost::asio::io_service& io_service_;
	tcp::acceptor acceptor_;
	std::set<chat_session_ptr> sessionList_;
};


typedef boost::shared_ptr<chat_server> chat_server_ptr;


int main()
{
	boost::asio::io_service io_service;
	tcp::endpoint endpoint(tcp::v4(), defaultPort);
	chat_server chatServer(io_service, endpoint);

	io_service.run();
    return 0;
}