使用Boost－用Asio實作簡易Echo Server

一、編寫代碼

注：以下代碼取自boost 1.40的示例代碼：

//
// async_tcp_echo_server.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#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、編譯代碼

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

注意：boost.asio庫依賴boost_system

三、運作 async_tcp_echo_server

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

四、用 telnet 指令作為用戶端測試

新開啟一個終端，注意：同樣要登入到Linux實驗室，執行： telnet localhost 8868

$ telnet localhost 8868
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
the first line    # 這是我們的輸入
the first line    # 這是伺服器 async_tcp_echo_server 的回應，以下類推
the second line
the second line
welcome to xuanyuan-soft.org.cn!
welcome to xuanyuan-soft.org.cn!      

五、關于Boost更多的資訊

請通路Boost的首頁：http://www.boost.org/

Linux下C/C++、ACE、Boost、高性能伺服器端應用 開發技術

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