boost official documentation chat program examples to explain
Packet format chat_message.hpp
<pre name = "code" class = "cpp"> <h3> packet chat_message.hpp </ H3>
// chat_message.hpp
// ~~~~~~~~~~~~~~~~
//
Copyright // (c) 2003-2013 Christopher M. Kohlhoff (chris AT Kohlhoff DOT COM)
//
. // at The Distributed an under the Boost Software License, Version 1.0 (See Accompanying
// File or Copy LICENSE_1_0.txt AT HTTP: // www.boost.org/LICENSE_1_0.txt)
// instance document from http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/examples/cpp03_examples.html no comment himself / // start looking, they also go detours, the paper wrote a detailed source notes, hoping that newcomers have less take some detours.
// first look at the structure of data packets:
// packet is divided into two parts, the first header is accounted 4bytes, each byte represents a number, which is a representation of up to 9999, is insufficient to fill the front 0;
// the length of the packet header size of a digital representation of the data portion.
#ifndef CHAT_MESSAGE_HPP
#define CHAT_MESSAGE_HPP
#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()//将报头的4字节字符串转换成数字
{
using namespace std; // For strncat and atoi.
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()//把数据部分大小编码成字符串
{
using namespace std; // For sprintf and memcpy.
char header[header_length + 1] = "";
sprintf(header, "%4d", body_length_);
memcpy(data_, header, header_length);
}
private:
char data_[header_length + max_body_length];
size_t body_length_;
};
#endif // CHAT_MESSAGE_HPPChat client chat_client.cpp
////////////////////////////////////////////////// ////////////////////////////////////////////////// ///
<H3>
</ H3> <H3>
<span style = "White Space-: pre-wrap"> chat client chat_client.cpp </ span>
</ H3>
<pre>
////// ////////////////////////////////////////////////// ///////////////////////////////////////////////
//
/ / chat_client.cpp
// ~~~~~~~~~~~~~~~
//
// Copyright (C) 2003-2013 Christopher M. Kohlhoff (Chris AT Kohlhoff DOT COM)
//
// The Distributed an under Software License the boost, Version 1.0. (See Accompanying
// File or Copy LICENSE_1_0.txt AT http://www.boost.org/LICENSE_1_0.txt)
//
// client boost the development of the document in real-time chat program end
// general idea is implemented: the client instance initialization socket, the connection created by the server, and constantly engaged in an asynchronous read operation (read data from the server)
// in the main thread, constantly read from the console message to be transmitted, and to post the io_service these messages, and then writes the asynchronous
// asynchronous operations are used to read and write socket
// this method is different from each open reading a thread, a writer thread, its advantages are thread does not have to wait to read and write data in case of a large number of concurrent read and write through asynchronous can improve resource utilization
#include <cstdlib>
#include <deque>
#include <iostream>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#include "chat_message.hpp"
using boost::asio::ip::tcp;
typedef std::deque<chat_message> chat_message_queue;
class chat_client
{
public:
chat_client(boost::asio::io_service& io_service,
tcp::resolver::iterator endpoint_iterator)
: io_service_(io_service),
socket_(io_service) //使得成员函数能直接使用这些变量
{
boost::asio::async_connect(socket_, endpoint_iterator,
boost::bind(&chat_client::handle_connect, this,
boost::asio::placeholders::error)); //所有的操作都采用异步的方式
}
void write(const chat_message& msg)
{
io_service_.post(boost::bind(&chat_client::do_write, this, msg)); //将消息主动投递给io_service
}
void close()
{
io_service_.post(boost::bind(&chat_client::do_close, this)); //这个close函数是客户端要主动终止时调用 do_close函数是从服务器端
//读数据失败时调用
}
private:
void handle_connect(const boost::system::error_code& error)
{
if (!error)
{
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.data(), chat_message::header_length), //读取数据报头
boost::bind(&chat_client::handle_read_header, this,
boost::asio::placeholders::error));
}
}
void handle_read_header(const boost::system::error_code& error)
{
if (!error && read_msg_.decode_header()) //分别处理数据报头和数据部分
{
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),//读取数据包数据部分
boost::bind(&chat_client::handle_read_body, this,
boost::asio::placeholders::error));
}
else
{
do_close();
}
}
void handle_read_body(const boost::system::error_code& error)
{
if (!error)
{
std::cout.write(read_msg_.body(), read_msg_.body_length()); //输出消息
std::cout << "\n";
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.data(), chat_message::header_length), //在这里读取下一个数据包头
boost::bind(&chat_client::handle_read_header, this,
boost::asio::placeholders::error)); //完成一次读操作（处理完一个数据包） 进行下一次读操作
}
else
{
do_close();
}
}
void do_write(chat_message msg)
{
bool write_in_progress = !write_msgs_.empty(); //空的话变量为false
write_msgs_.push_back(msg); //把要写的数据push至写队列
if (!write_in_progress)//队列初始为空 push一个msg后就有一个元素了
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_client::handle_write, this,
boost::asio::placeholders::error));
}
}
void handle_write(const boost::system::error_code& error)//第一个消息单独处理，剩下的才更好操作
{
if (!error)
{
write_msgs_.pop_front();//刚才处理完一个数据 所以要pop一个
if (!write_msgs_.empty())
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_client::handle_write, this,
boost::asio::placeholders::error)); //循环处理剩余的消息
}
}
else
{
do_close();
}
}
void do_close()
{
socket_.close();
}
private:
boost::asio::io_service& io_service_;
tcp::socket socket_;
chat_message read_msg_;
chat_message_queue write_msgs_;
};
int main(int argc, char* argv[])
{
try
{
if (argc != 3)
{
std::cerr << "Usage: chat_client <host> <port>\n";
return 1;
}
boost::asio::io_service io_service;
tcp::resolver resolver(io_service);
tcp::resolver::query query(argv[1], argv[2]); //输入ip（或域名）和端口号
tcp::resolver::iterator iterator = resolver.resolve(query);
chat_client c(io_service, iterator);
boost::thread t(boost::bind(&boost::asio::io_service::run, &io_service));
char line[chat_message::max_body_length + 1];
while (std::cin.getline(line, chat_message::max_body_length + 1))
{
using namespace std; // For strlen and memcpy.
chat_message msg;
msg.body_length(strlen(line));
memcpy(msg.body(), line, msg.body_length());
msg.encode_header();
c.write(msg);
}
c.close();
t.join();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}Chat server chat_server.cpp
//
// chat_server.cpp
// ~~~~~~~~~~~~~~~
//
// Copyright (C) 2003-2013 Christopher M. Kohlhoff (Chris AT Kohlhoff DOT COM)
//
// an under the Boost Software License at The Distributed, Version 1.0. (See Accompanying
// File or Copy LICENSE_1_0.txt AT http://www.boost.org/LICENSE_1_0.txt)
//
// server-side program, first open a chat_server, with initially and then io_service chat_room;. a time to open a server chat_room, the effect chat_room 1 // store user information 2. to achieve user information join and leave 3. save receives from each client receives 4 message to each client linked to the tail write_msgs
// each connected client (Socket) to open and add a new chat_session chat_room chat_session only asynchronous read and write separately implemented for each operation of a client //
#include <algorithm>
#include <cstdlib>
#include <deque>
#include <iostream>
#include <list>
#include <set>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <boost/asio.hpp>
#include "chat_message.hpp"
using boost::asio::ip::tcp;
//----------------------------------------------------------------------
typedef std::deque<chat_message> chat_message_queue;
//----------------------------------------------------------------------
class chat_participant
{
public:
virtual ~chat_participant() {}
virtual void deliver(const chat_message& msg) = 0; //后面需要重载
};
typedef boost::shared_ptr<chat_participant> chat_participant_ptr;
//----------------------------------------------------------------------
class chat_room
{
public:
void join(chat_participant_ptr participant)
{
participants_.insert(participant);
std::for_each(recent_msgs_.begin(), recent_msgs_.end(),
boost::bind(&chat_participant::deliver, participant, _1));
}
void leave(chat_participant_ptr participant)
{
participants_.erase(participant);
}
//将从某个客户端收到的消息挂到 每一个客户端的write_msgs队尾 具体见chat_participant::deliver
void deliver(const chat_message& msg)
{
recent_msgs_.push_back(msg);
while (recent_msgs_.size() > max_recent_msgs)
recent_msgs_.pop_front(); //room中保存的消息数有限
std::for_each(participants_.begin(), participants_.end(),
boost::bind(&chat_participant::deliver, _1, boost::ref(msg)));
}
private:
std::set<chat_participant_ptr> participants_;//用set来保存用户信息
enum { max_recent_msgs = 100 };
chat_message_queue recent_msgs_;//用来保存从某个客户端接收到的信息
};
//----------------------------------------------------------------------
class chat_session
: public chat_participant,
public boost::enable_shared_from_this<chat_session>
{
public:
chat_session(boost::asio::io_service& io_service, chat_room& room)
: socket_(io_service),
room_(room)
{
}
tcp::socket& socket()
{
return socket_;
}
void start()//每生成一个新的chat_session都会调用
{
room_.join(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)); //异步读客户端发来的消息
}
void deliver(const chat_message& msg)
{
bool write_in_progress = !write_msgs_.empty();
write_msgs_.push_back(msg); //把room中保存的消息挂到write_msgs队尾
if (!write_in_progress)
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_session::handle_write, 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
{
room_.leave(shared_from_this());
}
}
void handle_read_body(const boost::system::error_code& error)
{
if (!error)
{
room_.deliver(read_msg_);
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
{
room_.leave(shared_from_this());
}
}
void handle_write(const boost::system::error_code& error)
{
if (!error)
{
write_msgs_.pop_front();
if (!write_msgs_.empty())
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_session::handle_write, shared_from_this(),
boost::asio::placeholders::error)); //服务器端将收到的消息送给所有的客户端（广播的方式）
}
}
else
{
room_.leave(shared_from_this());
}
}
private:
tcp::socket socket_;
chat_room& room_;
chat_message read_msg_;
chat_message_queue write_msgs_;
};
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) //全局只有一个io_service和一个acceptor
{
start_accept();
}
void start_accept()
{
chat_session_ptr new_session(new chat_session(io_service_, room_));
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(); //每连接上一个socket都会调用
}
private:
boost::asio::io_service& io_service_;
tcp::acceptor acceptor_;
chat_room room_; //chat_room中没有重载构造函数 所以会直接调用默认构造函数
};
typedef boost::shared_ptr<chat_server> chat_server_ptr;
typedef std::list<chat_server_ptr> chat_server_list;
//----------------------------------------------------------------------
int main(int argc, char* argv[])
{
try
{
if (argc < 2)
{
std::cerr << "Usage: chat_server <port> [<port> ...]\n";
return 1;
}
boost::asio::io_service io_service;
chat_server_list servers;
for (int i = 1; i < argc; ++i)
{
using namespace std; // For atoi.
tcp::endpoint endpoint(tcp::v4(), atoi(argv[i]));
chat_server_ptr server(new chat_server(io_service, endpoint));
servers.push_back(server);
}
io_service.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}