visual c++网络通讯编程实用案例精选中

 DWORD dwFlags;
 InternetGetConnectedState(&dwFlags, 0);
 CHAR strAgent[64];
 sprintf(strAgent, "Agent%ld", timeGetTime());
 HINTERNET hOpen;
 if(!(dwFlags & INTERNET_CONNECTION_PROXY))
  hOpen = InternetOpenA(strAgent, INTERNET_OPEN_TYPE_PRECONFIG_WITH_NO_AUTOPROXY, NULL, NULL, 0);
 else
  hOpen = InternetOpenA(strAgent, INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
 if(!hOpen)
 {
  AfxMessageBox("Internet连接错误!");
  return -1;
 }

 DWORD dwSize;
 CHAR   szHead[] = "Accept: */*\r\n\r\n";
 VOID* szTemp[16384];
 HINTERNET  hConnect;
 CFile file;

 if ( !(hConnect = InternetOpenUrlA ( hOpen, szUrl, szHead,
   lstrlenA (szHead), INTERNET_FLAG_DONT_CACHE | INTERNET_FLAG_PRAGMA_NOCACHE | INTERNET_FLAG_RELOAD, 0)))
 {
    AfxMessageBox("不能打开该URL!");
    return -1;
 }

 if  (file.Open(szFileName,CFile::modeWrite|CFile::modeCreate)==FALSE )
 {
    AfxMessageBox("不能打开本地的文件!");
   return -1;
 }

 DWORD dwByteToRead = 0;
 DWORD dwSizeOfRq = 4;
 DWORD dwBytes = 0;

    if (!HttpQueryInfo(hConnect, HTTP_QUERY_CONTENT_LENGTH | HTTP_QUERY_FLAG_NUMBER,
                  (LPVOID)&dwByteToRead, &dwSizeOfRq, NULL))
 {
  dwByteToRead = 0;
 }

 DWORD start;
 DWORD end;
 DWORD time;
 CString tempstring;
 time = 10;
 start = timeGetTime();
 do
 {
  if (!InternetReadFile (hConnect, szTemp, 16384,  &dwSize))
  {
   AfxMessageBox("读文件出错!");
   file.Close();
   return -1;
  }
  if (dwSize==0)
   break;
  else
   file.Write(szTemp,dwSize);
  dwBytes+=dwSize;
  if(dwByteToRead)
  {
   tempstring.Format("%d%%",(dwBytes*100)/dwByteToRead);
   SetDlgItemText(IDC_PERCENT_TEXT,tempstring);
  }
  FLOAT fSpeed = 0;
  fSpeed = (float)dwBytes;
  fSpeed /= ((float)time)/1000.0f;
  fSpeed /= 1024.0f;
  tempstring.Format("%dKB/s",fSpeed);
  SetDlgItemText(IDC_SPEED_TEXT,tempstring);
  end = timeGetTime();
  time = end - start;
  if(time == 0)
   time = 10;
 }while (TRUE);

 file.Close();
 InternetCloseHandle(hOpen);