tcp_sync_server and tcp_sync_client

#include <iostream>

#include <fstream>

#include <sstream>

#include <boost/asio.hpp>

using namespace std;

using boost::asio::ip::tcp;

const char* serviceList =  "        Services "      

" ************************** "

     " [1] Get current time. "

     " [2] Who's online. "

     " [3] Get system info. "

     " ************************** "

     "Please pick a service[1-3]: ";

ifstream fin;

void getResult(const string& cmdPrefix, const char* outputFile,

string& res) {

    // cmd == "w > who"

    string cmd(cmdPrefix + outputFile);

    system(cmd.c_str());//将字符串解析为系统命令，然后执行      

      fin.open(outputFile);//存在打开文件，否则创建             

 if (fin) {  ostringstream os; os << fin.rdbuf(); res = os.str();   

 }

   

if (fin.is_open()) { fin.close();     }

}

string getServiceContent(const int& select) {

    string res;

    switch (select) { //time(0)获取当前时间，ctime将时间转换成字

符串。      case 1: {    time_t t = time(0); res = ctime(&t);  break;   

 }      case 2: getResult("w > ", "who", res);    break;   case 3: getResult("uname -a > ", "uname", res); break;      

default:  res = "Sorry, no such service. ";  break;     }

   

return res; }              

int main() {     try {   boost::asio::io_service io_service; // #1  

       tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4     //tcp::endpoint(端点)由ip地址，端口号，协议版本组成。

(), 8868)); // #2    for (;;) {   tcp::socket socket(io_service); // #3   /不断创建socket对象，并且与acceptor进行关联           

acceptor.accept(socket); // #4

            // 1, send service list to client

boost::system::error_code ignored_error;            

boost::asio::write(socket, boost::asio::buffer(serviceList),     //buffer相当于显示器的一个缓冲，临时存储数据的一个容器

      boost::asio::transfer_all(), ignored_error);  //自我感觉read和write是一个固定套路

            // 2, receive selection from client              char selection[20];

size_t n = socket.read_some(boost::asio::buffer(selection),      

              ignored_error);             // 3, send response            

string response = getServiceContent(atoi(selection));            

boost::asio::write(socket, boost::asio::buffer(response),        

            boost::asio::transfer_all(), ignored_error);        

} // #6     } catch (std::exception& e) {

        std::cerr << e.what() << std::endl;     }

    return 0; }

************************************************************************

/*  * tcp_sync_client.cpp  *  *  Created on: 2010-3-16 上午11:47:12  *      Author: kwarph  *         Web: http://www.xuanyuan-soft.cn  *        Mail: kwarph@gmail.com  */

#include <iostream>

#include <boost/asio.hpp>

using namespace std;

using boost::asio::ip::tcp;

int main(int argc, char* argv[]) {

    try {         // 1, 创建io_service对象        

boost::asio::io_service io_service;

        // 2, 创建resolver对象关联到io_service对象

        tcp::resolver resolver(io_service);

        // 3, 创建一个查询对象

        tcp::resolver::query query("localhost", "8868");

        // 4, 用resolver对象和查询对象获取可用服务器地址

        tcp::resolver::iterator endpoint_iterator = resolver.resolve(query); //把用resolve解析query的即localhost首地址给endpoint_iterator      tcp::resolver::iterator end;

//iterator就是endpoint的指针

        // 5, 创建tcp::socket对象，关联到io_service

        tcp::socket socket(io_service);

        // 6, socket对象发起到服务器端的同步连接操作

        boost::system::error_code error = boost::asio::error::host_not_found;

        while (error && endpoint_iterator != end) {             socket.close();

            socket.connect(*endpoint_iterator++, error);         }

        if (error) // 如果没有一个地址能连接成功，则抛出异常

            throw boost::system::system_error(error);

        // 7, 一系列 同步read()和write()

        char buf[512];

        //1. receive service list from server

        //        size_t len = socket.read_some(boost::asio::buffer(buf), error);         //

　　 size_t len = socket.receive(boost::asio::buffer(buf), 0, error);

      //2.confirm size of info with server//进行read操作时，先socket.read_some r然后才是asio::read. write则相反，需先asio::write,再socket.write_some,b并且还要socket.send

   size_t len = boost::asio::read(socket, boost::asio::buffer(buf), boost::asio::transfer_at_least(1), error);//asio读写时的参数更多

        buf[len] = '';         cout << buf;

        string selection;         cin >> selection;

        //3. send selection to server //

 boost::asio::write(socket, boost::asio::buffer(selection), // 

               boost::asio::transfer_all(), error);

//        socket.write_some(boost::asio::buffer(selection,selection.size()), error);

        socket.send(boost::asio::buffer(selection,selection.size()),0, error);

        //4. receive response from server

    len = socket.read_some(boost::asio::buffer(buf), error);

        buf[len] = '';          cout << buf;     }  catch (std::exception& e) {

        std::cerr << e.what() << std::endl;     }

    return 0; }