Boost asio学习笔记之二—— 网络编程

boost库中的网络编程的例子比较复杂，不太好理解，所以，从网上找了一个简单点的例子。网址如下：http://blog.chinaunix.net/u3/93184/showart_1846119.html.经过修改，可以运行。

服务器代码：

Servier.cpp

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <iostream>
using boost::asio::ip::tcp;
#define max_len 1024

class clientSession
:public boost::enable_shared_from_this<clientSession>
{
public:
clientSession(boost::asio::io_service& ioservice)
:m_socket(ioservice)
{
memset(data_,‘\0′,sizeof(data_));
}
~clientSession()
{}
tcp::socket& socket()
{
return m_socket;
}
void start()
{
boost::asio::async_write(m_socket,
boost::asio::buffer(“link successed!”),
boost::bind(&clientSession::handle_write,shared_from_this(),
boost::asio::placeholders::error));

/*async_read跟客户端一样，还是不能进入handle_read函数,如果你能找到问题所在，请告诉我，谢谢*/

// --已经解决，boost::asio::async_read(...)读取的字节长度不能大于数据流的长度，否则就会进入


// ioservice.run()线程等待，read后面的就不执行了。
//boost::asio::async_read(m_socket,boost::asio::buffer(data_,max_len),

//         boost::bind(&clientSession::handle_read,shared_from_this(),

//         boost::asio::placeholders::error));


//max_len可以换成较小的数字，就会发现async_read_some可以连续接收未收完的数据

m_socket.async_read_some(boost::asio::buffer(data_,max_len),
boost::bind(&clientSession::handle_read,shared_from_this(),
boost::asio::placeholders::error));
}
private:
void handle_write(const boost::system::error_code& error)
{

if(error)
{
m_socket.close();
}

}
void handle_read(const boost::system::error_code& error)
{

if(!error)
{
std::cout << data_ << std::endl;
//boost::asio::async_read(m_socket,boost::asio::buffer(data_,max_len),

//     boost::bind(&clientSession::handle_read,shared_from_this(),

//     boost::asio::placeholders::error));

m_socket.async_read_some(boost::asio::buffer(data_,max_len),
boost::bind(&clientSession::handle_read,shared_from_this(),
boost::asio::placeholders::error));
}
else
{
m_socket.close();
}

}
private:
tcp::socket m_socket;
char data_[max_len];
};

class serverApp
{
typedef boost::shared_ptr<clientSession> session_ptr;
public:
serverApp(boost::asio::io_service& ioservice,tcp::endpoint& endpoint)
:m_ioservice(ioservice),
acceptor_(ioservice,endpoint)
{
session_ptr new_session(new clientSession(ioservice));
acceptor_.async_accept(new_session->socket(),
boost::bind(&serverApp::handle_accept,this,boost::asio::placeholders::error,
new_session));
}
~serverApp()
{
}
private:
void handle_accept(const boost::system::error_code& error,session_ptr& session)
{
if(!error)
{
std::cout << “get a new client!” << std::endl;
//实现对每个客户端的数据处理

session->start();
//在这就应该看出为什么要封session类了吧，每一个session就是一个客户端

session_ptr new_session(new clientSession(m_ioservice));
acceptor_.async_accept(new_session->socket(),
boost::bind(&serverApp::handle_accept,this,boost::asio::placeholders::error,
new_session));
}
}
private:
boost::asio::io_service& m_ioservice;
tcp::acceptor acceptor_;
};

int main(int argc , char* argv[])
{
boost::asio::io_service myIoService;
short port = 8100/*argv[1]*/;
//我们用的是inet4

tcp::endpoint endPoint(tcp::v4(),port);
//终端（可以看作sockaddr_in）完成后，就要accept了

serverApp sa(myIoService,endPoint);
//数据收发逻辑

myIoService.run();
return 0;
}

客户端代码：

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
using boost::asio::ip::tcp;

class client
{
public:
client(boost::asio::io_service& io_service,tcp::endpoint& endpoint)
: socket(io_service)//这里就把socket实例化了
{
//连接服务端 connect
socket.async_connect(endpoint,
boost::bind(&client::handle_connect,this,boost::asio::placeholders::error)
);
memset(getBuffer,‘\0′,1024);
}
~client()
{}
private:
void handle_connect(const boost::system::error_code& error)
{
if(!error)
{
//一连上，就向服务端发送信息
boost::asio::async_write(socket,boost::asio::buffer(“hello,server!”),
boost::bind(&client::handle_write,this,boost::asio::placeholders::error));

/**读取服务端发下来的信息
*这里很奇怪，用async_read根本就不能进入handle_read函数
**/

// --已经解决，boost::asio::async_read(...)读取的字节长度不能大于数据流的长度，否则就会进入


// ioservice.run()线程等待，read后面的就不执行了。

//boost::asio::async_read(socket,
//     boost::asio::buffer(getBuffer,1024),
//     boost::bind(&client::handle_read,this,boost::asio::placeholders::error)
//    );
socket.async_read_some(boost::asio::buffer(getBuffer,1024),
boost::bind(&client::handle_read,this,boost::asio::placeholders::error)
);

}
else
{
socket.close();
}
}
void handle_read(const boost::system::error_code& error)
{
if(!error)
{
std::cout << getBuffer << std::endl;
//boost::asio::async_read(socket,
//         boost::asio::buffer(getBuffer,1024),
//         boost::bind(&client::handle_read,this,boost::asio::placeholders::error)
//        );

//这样就可以实现循环读取了，相当于while（1）
//当然，到了这里，做过网络的朋友就应该相当熟悉了，一些逻辑就可以自行扩展了
//想做聊天室的朋友可以用多线程来实现
socket.async_read_some(
boost::asio::buffer(getBuffer,1024),
boost::bind(&client::handle_read,this,boost::asio::placeholders::error)
);
}
else
{
socket.close();
}
}
void handle_write(const boost::system::error_code& error)
{
}

private:
tcp::socket socket;
char getBuffer[1024];
};

int main(int argc,char* argv[])
{
//if(argc != 3)
//{
// std::cerr << “Usage: chat_client <host> <port>\n”;
//    return 1;
//}

//我觉IO_SERVICE是一个基本性的接口，基本上通常用到的类实例都需要通过它来构造
//功能我们可以看似socket
boost::asio::io_service io_service;
//这个终端就是服务器
//它的定义就可以看作时sockaddr_in,我们用它来定义IP和PORT
tcp::endpoint endpoint(boost::asio::ip::address_v4::from_string("192.168.1.119"/*argv[1]*/),8100/*argv[2]*/);
//既然socket和sockaddr_in已经定义好了，那么，就可以CONNECT了
//之所以为了要把连接和数据处理封成一个类，就是为了方便管理数据,这点在服务端就会有明显的感觉了
boost::shared_ptr<client> client_ptr(new client(io_service,endpoint));
//执行收发数据的函数
io_service.run();
return 0;
}

修改192.168.1.119为127.0.0.1，然后先运行server，再运行client，一切ok.