VC:检测网络连接的方法

方法一：

#include "stdafx.h"
#include "windows.h"
#include <Sensapi.h>
#include <iostream>
#include <Wininet.h>

#pragma comment(lib, "Sensapi.lib")
#pragma comment(lib, "Wininet.lib")

using namespace  std;

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
    BOOL isConnect;
    DWORD dw;
    isConnect = ::IsNetworkAlive( &dw );
    while ()
    {
        if(isConnect)
            cout << "IsNetworkAlive连接" <<endl;
        else
            cout << "IsNetworkAlive未连接" <<endl;
        cout<< "---------------------------------" <<endl;

        DWORD dw2;
        BOOL ret = InternetGetConnectedState(&dw2, );
        if (ret)
            cout << "InternetGetConnectedState连接" <<endl;
        else
            cout << "InternetGetConnectedState未连接" <<endl;
        cout<< "**********************************"  <<endl;

        BOOL bConnected = InternetCheckConnection(_T("http://www.baidu.com"), FLAG_ICC_FORCE_CONNECTION, );
        if (bConnected)
            cout << "InternetCheckConnection连接" <<endl;
        else
            cout << "InternetCheckConnection未连接" <<endl;
        cout<< "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%"  <<endl;

        //IsDestinationReachable(_T("http://www.google.com"), )    

        cout<<endl<<endl<<endl;
        Sleep();

    }
    getchar();
    return ;
}

方法二：

// Connect to www.baidu.com.
      HINTERNET hConnect = InternetConnect(hSession,
                                    "www.baidu.com",
                                    INTERNET_INVALID_PORT_NUMBER,
                                    "",
                                    "",
                                    INTERNET_SERVICE_HTTP,
                                    ,
                                    );

      // Request the file /index.php from the server.
      HINTERNET hUrl = HttpOpenRequest(hConnect,
                                     "GET",
                                     "/index.php",
                                     HTTP_VERSION,
                                     NULL,
                                     ,
                                     INTERNET_FLAG_DONT_CACHE,
                                     );

      // Add request headers
      TCHAR szHeaders[] = "Accept: text/*\r\n";
      BOOL bAddHeaders = HttpAddRequestHeaders(hConnect,
                                  szHeaders,
                                  lstrlen(szHeaders),
                                  HTTP_ADDREQ_FLAG_ADD);

      // Send the request.
      BOOL bSendRequest = HttpSendRequest(hUrl, NULL, , , );

      if(hUrl == NULL)
      {
              printf("InternetOpenUrl Error......\n");
              InternetCloseHandle(hSession);
              return ;
      }

      BOOL bRet = HttpQueryInfo(hUrl, HTTP_QUERY_STATUS_CODE|HTTP_QUERY_FLAG_NUMBER, &dwStatusCode, &dwSizeOfStatusCode, NULL);
      if(!bRet)
      {
             printf("HttpQueryInfo Error......\n");
             return ;
      }

      // Key point
      if( == dwStatusCode)
      {
             InternetCloseHandle(hUrl) ;
             InternetCloseHandle(hSession) ;
             return ;
      }

方法三：

//本机网络连接类型(成功)
#define  NET_TYPE_RAS_DIAL_UP_CONNECT_NET           0x01    //上网类型：采用RAS拨号连接上网    0x01
#define  NET_TYPE_LAN_CONNECT_NET                   0x02    //上网类型：采用网卡通过局域网上网 0x02
#define  NET_TYPE_PROXY_CONNECT_NET                 0x04    //上网类型：使用代理服务器上网     0x04
#define  NET_TYPE_RAS_INSTALL                       0x10    //RAS安装                        0x10  

//本机网络连接(失败)
#define  NET_TYPE_NO_CONNECT_NET                    0x41    //未连接到网络
#define  NET_STATE_VALID_CONNECT_NOCONNECT_NET      0x40    //可以联网，但当前不可用    0x40
#define  NET_STATE_MODEM_BUSY                       0x08    //调制解调器 繁忙           0x08
#define  NET_STATE_SYSTEM_OFFLINE_MODE              0x20    //系统脱机模式              0x20  

CheckNet()
{
if(!InternetGetConnectedState(&dwOnline, ))
    {
        if (dwOnline & INTERNET_CONNECTION_CONFIGURED )
        {
            return NET_STATE_VALID_CONNECT_NOCONNECT_NET;
        }
        if (dwOnline & INTERNET_CONNECTION_MODEM_BUSY)
        {
            return NET_STATE_MODEM_BUSY;
        }
        if (dwOnline & INTERNET_CONNECTION_OFFLINE)
        {
            return NET_STATE_SYSTEM_OFFLINE_MODE;
        }  

        return NET_TYPE_NO_CONNECT_NET;
    }  

    if ( dwOnline& INTERNET_CONNECTION_MODEM )      //上网类型：采用RAS拨号连接上网
    {
        return  NET_TYPE_RAS_DIAL_UP_CONNECT_NET;
    }  

    else if ( dwOnline&INTERNET_CONNECTION_LAN  )  //上网类型：采用网卡通过局域网上网
    {
        return NET_TYPE_LAN_CONNECT_NET;
    }  

    else if ( dwOnline& INTERNET_CONNECTION_PROXY) //在线：代理
    {
        return NET_TYPE_PROXY_CONNECT_NET;
    }  

    else if ( dwOnline&INTERNET_CONNECTION_MODEM_BUSY ) //MODEM被其他非INTERNET连接占用
    {
        return NET_TYPE_RAS_INSTALL;
    }
}