select模型实例

#include <WINSOCK2.H>
#include <iostream>
#pragma comment(lib,"ws2_32")

int main()
{
using namespace std;
WSADATA wsaData;
WORD sockVersion=MAKEWORD(2,2);
if (WSAStartup(sockVersion,&wsaData)!=0)
{
   cout<<"套接字库加载失败！";
   exit(0);
}
if ( LOBYTE( wsaData.wVersion ) != 2 || HIBYTE( wsaData.wVersion ) != 2 ) 
{
   WSACleanup( );
   cout<<"套接字库加载失败！";
   exit(0);
}
USHORT nPort=4567;
SOCKET sListen=socket(AF_INET,SOCK_STREAM,0);
sockaddr_in addrin;
addrin.sin_addr.S_un.S_addr=INADDR_ANY;
addrin.sin_family=AF_INET;
addrin.sin_port=htons(nPort);

if (SOCKET_ERROR==bind(sListen,(sockaddr*)&addrin,sizeof(sockaddr)))
{
   cout<<"绑定失败！\n";
   return -1;
}
//进入监听模式
if (SOCKET_ERROR==listen(sListen,5))
{
   cout<<"监听失败！\n";
   return -1;
}

//select模型处理过程
fd_set fdSocket;
FD_ZERO(&fdSocket);
FD_SET(sListen,&fdSocket);
while (true)
{
   //将fdSocket集合的一个拷贝fdRead传递给Select函数
   //当有事件发生时，Select函数移除fdRead集合中没有未决I/O操作的套接字句柄，然后返回
   fd_set fdRead=fdSocket;
   int nRet=select(0,&fdRead,NULL,NULL,NULL); //等待时间设为NULL,让它知道有时间发生时候才返回
   if (nRet>0)
   {
    //通过原来fdSocket集合与Select处理过的fdRead集合比较，确定有哪些套接字有未决I/O，并进一步处理
    for (int i=0;i<(int)fdSocket.fd_count;i++)
    {
     if (FD_ISSET(fdSocket.fd_array[i],&fdRead))
     {
      if (sListen==fdSocket.fd_array[i])         //监听套接字接收到新连接
      {
       if (fdSocket.fd_count<FD_SETSIZE)      //小于fs_set结构的套接字最大数量
       {
        sockaddr_in addrRemote;
        int nAddrlen=sizeof(addrRemote);
        SOCKET NewSocket=accept(sListen,(sockaddr*)&addrRemote,&nAddrlen);
        FD_SET(NewSocket,&fdSocket);
        cout<<"接收到"<<inet_ntoa(addrRemote.sin_addr)<<"的连接\n";
       }
       else
       {
        cout<<"连接数已经到达顶限\n";
        continue;
       }
      }
      else
      {
       char szText[256];
       int nRecv=recv(fdSocket.fd_array[i],szText,256,0);
       if (nRecv>0)                                //数据可读
       {
        szText[nRecv]='\0';
        cout<<"接收到数据："<<szText<<endl;
       }
       else                                        //连接关闭，重启或者中断
       {
        closesocket(fdSocket.fd_array[i]);
        FD_CLR(fdSocket.fd_array[i],&fdSocket);
       }
      }
     }
    }
   }
   else
   {
    cout<<"Select执行失败！\n";
    break;
   }
}
    return 0;
}