Boost－用Asio实现简易Echo Server

#include <cstdlib>
#include <iostream>
#include <boost/bind.hpp>
#include <boost/asio.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() {
socket_.async_read_some(boost::asio::buffer(data_, max_length),
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) {
boost::asio::async_write(socket_, boost::asio::buffer(data_,
bytes_transferred), boost::bind(&session::handle_write,
this, boost::asio::placeholders::error));
} else {
delete this;
}
}

void handle_write(const boost::system::error_code& error) {
if (!error) {
socket_.async_read_some(boost::asio::buffer(data_, max_length),
boost::bind(&session::handle_read, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
} else {
delete this;
}
}

private:
tcp::socket socket_;
enum {
max_length = 1024
};
char data_[max_length];
};

class server {
public:
server(boost::asio::io_service& io_service, short port) :
io_service_(io_service), acceptor_(io_service, tcp::endpoint(tcp::v4(),
port)) {
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();
new_session = new session(io_service_);
acceptor_.async_accept(new_session->socket(), boost::bind(
&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
} else {
delete new_session;
}
}

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

int main(int argc, char* argv[]) {
try {
if (argc != 2) {
std::cerr << "Usage: async_tcp_echo_server <port>\n";
return 1;
}

boost::asio::io_service io_service;

using namespace std;
// For atoi.
server s(io_service, atoi(argv[1]));

io_service.run();
} catch (std::exception& e) {
std::cerr << "Exception: " << e.what() << "\n";
}

return 0;
}

二、编译代码

$ g++ －g3 －Wall -o"async_tcp_echo_server" async_tcp_echo_server.cpp -lboost_system

注意：boost.asio库依赖boost_system

三、运行 async_tcp_echo_server

$ ./async_tcp_echo_server 8868   # 8868 是async_tcp_echo_server listen的端口号

四、用 telnet 命令作为客户端测试

新开启一个终端，注意：同样要登录到Linux实验室，执行： telnet localhost 8868

$ telnet localhost 8868

Trying ::1...

Trying 127.0.0.1...

Connected to localhost.

Escape character is '^]'.

the first line    # 这是我们的输入

the first line    # 这是服务器 async_tcp_echo_server 的回应，以下类推

the second line

the second line

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