HTTP页面下载（CInternetSession 和 CHttpFile应用)

//http下载
#include 
#include 

DWORD HttpRead(LPCTSTR pstrURL, CString &szReturn)
{
  DWORD dwError = 0;
  
  //初始化Socket
  do
  {
    if(!AfxSocketInit())
    {
      dwError = ERROR_INTERNET_TCPIP_NOT_INSTALLED;
      ASSERT(FALSE);
      break;
    }
  
    CInternetSession session;
    CHttpFile* pFile = NULL;
    try
    {
      if((pFile = (CHttpFile*)session.OpenURL(pstrURL)) != NULL)
      {
        DWORD dwRet = 0;
        pFile->QueryInfoStatusCode(dwRet);
        
        while (dwRet == HTTP_STATUS_OK)
        {
          char szBuff[1025];
          memset(szBuff, 0, sizeof(szBuff));
          UINT nRead = pFile->Read(szBuff, 1024);
          if(nRead > 0)
          {
            szReturn += szBuff;
          }
          else
          {
            break;
          }
        }
        pFile->Close();
      }
    }
    catch (CInternetException* pEx)
    {
      //catch errors from WinInet
      dwError = pEx->m_dwError;
     #ifdef _DEBUG
      pEx->ReportError();
     #endif
      pEx->Delete();
    }

    //结束清理
    if(pFile){ delete pFile; pFile = NULL; }
    session.Close();  
  }while(0);
      
  return dwError;
}