HTTP服务器上断点下载文件

时间：2022-08-26 17:49:38
从HTTP服务器上下载一个文件有很多方法，“热心”的微软提供了 WinInet 类，用起来也很方便。当然，我们也可以自己实现这些功能，通过格式化请求头很容易就能实现断点续传和检查更新等等功能 。
  1. 连接主机
  2. 格式化请求头
  3. 设置接收,发送超时
    　　

         要想从服务器下载文件，首先要向服务器发送一个请求。HTTP 请求头由若干行字符串组成。下面结合实例说说 HTTP 请求头的格式。假设要下载 http://www.sina.com.cn/index.html 这个网页 ，那么请求头的写法如下：

第1行：方法，请求的内容，HTTP协议的版本
下载一般可以用GET方法，请求的内容是“/index.html”，HTTP协议的版本是指浏览器支持的版本，对于下载软件来说无所谓，所以用1.1版 “HTTP/1.1”；
“GET /index.html HTTP/1.1”

第2行：主机名，格式为“Host:主机”
在这个例子中是：“Host:www.sina.com.cn”

第3行：接受的数据类型，下载软件当然要接收所有的数据类型，所以：
“Accept:*/*”

第4行：指定浏览器的类型
有些服务器会根据客户服务器种类的不同会增加或减少一些内容，在这个例子中可以这样写：

“User-Agent:Mozilla/4.0 (compatible; MSIE 5.00; Windows 98)”

第5行：连接设置
设定为一直保持连接：“Connection:Keep-Alive”

第6行：若要实现断点续传则要指定从什么位置起接收数据，格式如下：

“Range: bytes=起始位置 - 终止位置”

比如要读前500个字节可以这样写：“Range: bytes=0 - 499”；从第 1000 个字节起开始下载：

“Range: bytes=999 -”

最后，别忘了加上一行空行，表示请求头结束。整个请求头如下：

GET /index.html HTTP/1.1
Host:www.sina.com.cn
Accept:*/*
User-Agent:Mozilla/4.0 (compatible; MSIE 5.00; Windows 98)
Connection:Keep-Alive
下面用例子看看如何进行断点的下载吧






//  DownloadFile.h: interface for the CDownloadFile class.
//
// ////////////////////////////////////////////////////////////////////

# if   ! defined(AFX_DOWNLOADFILE_H__E9A59779_BEF9_4A78_8D0E_ED8C9498E07C__INCLUDED_)
#define AFX_DOWNLOADFILE_H__E9A59779_BEF9_4A78_8D0E_ED8C9498E07C__INCLUDED_

# if  _MSC_VER  >   1000
#pragma once
#endif  //  _MSC_VER > 1000

#define NOTIFY_MSG_WPARAM_GENDOWNFILEID                 0x01

#define NOTIFY_MSG_LOW_WPARAM_FULLSIZE                 0x10
#define NOTIFY_MSG_LOW_WPARAM_CURRENTSIZE             0x20
#define NOTIFY_MSG_LOW_WPARAM_DOWNSIZE                 0x30
#define NOTIFY_MSG_LOW_WPARAM_DOWNSPEED                 0x40

class CDownloadFile  
{
public:
    BOOL OpenRedirectHttpURL(CString  & strOldLocation,CInternetSession  & cSession);
    BOOL DownLoadFile(LPCTSTR lpFileURL,LPCTSTR lpSaveFile);
    CDownloadFile();
    virtual  ~ CDownloadFile();
    LPCTSTR GetSavedFileName() {  return  m_strSaveToFile;}
    LPCTSTR GetDownURL() {  return  m_strFileURL;}

public:
    WORD GenFileID();
     void  RegisterNotifyWindow(DWORD dwThreadID,HWND hWnd,DWORD dwMsg);
    BOOL GetUNCFile();
    bool m_bForceReload;
    DWORD m_TimeOut;
    WORD m_wFileID;

protected:
    DWORD m_dwThreadID;
     void  PostNotifyMessage(WPARAM wParam, LPARAM lParam);
    DWORD m_dwMsgID;
    HWND m_hNotify;
    BOOL GetFtpFile(CInternetSession  & cSession);
    BOOL GetHttpFile(CInternetSession  & cSession);
    CString m_strTmpFileName;
    CString m_strFileURL;
    CString m_strSaveToFile;
    CString    m_rawHeaders;
     float   m_transferRate;
    DWORD    m_infoStatusCode;
};

#endif  //  !defined(AFX_DOWNLOADFILE_H__E9A59779_BEF9_4A78_8D0E_ED8C9498E07C__INCLUDED_)


//  DownloadFile.cpp: implementation of the CDownloadFile class.
//
// ////////////////////////////////////////////////////////////////////

#include  " stdafx.h "
#include  " DownloadFile.h "

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

#include  " shlwapi.h "
#pragma comment( lib, " shlwapi.lib "  )

#ifdef _DEBUG
#undef THIS_FILE
static  char  THIS_FILE[] = __FILE__;
#define  new  DEBUG_NEW
#endif

#define BUFFER_SIZE  4095

const TCHAR szHeaders[]  =  _T( " Accept: */*/r/nUser-Agent:  Mozilla/4.0 (compatible; MSIE 5.00; Windows 98)/r/n " );

 // ////////////////////////////////////////////////////////////////////
//  Construction/Destruction
// ////////////////////////////////////////////////////////////////////

CDownloadFile::CDownloadFile()
{
    m_TimeOut  =   0 ;
    m_bForceReload  =   true ;
    m_dwThreadID  =   0 ;
    m_hNotify  =  NULL;
    m_dwMsgID  =   0 ;
    m_wFileID  =   0 ;
}

CDownloadFile:: ~ CDownloadFile()
{

}

BOOL CDownloadFile::DownLoadFile(LPCTSTR lpFileURL, LPCTSTR lpSaveFile)
{
    BOOL bRet  =  FALSE;
     if  (  ! ::PathIsURL(lpFileURL) )
    {
         return  bRet;
    }
    m_strSaveToFile  =  lpSaveFile;
    m_strFileURL  =  lpFileURL;
    m_strTmpFileName  =  lpSaveFile;
    m_strTmpFileName  +=  _T( " .df! " );
    CString strServer,strObject;INTERNET_PORT nPort;
    CString strAgentCaption  =   _T( " Update Download  " ) ;
    strAgentCaption  +=  ::PathFindFileName(lpSaveFile);
    DWORD dwFlags  =   0 ;
    InternetGetConnectedState( & dwFlags,  0 );
    CInternetSession session (strAgentCaption,  1 ,
        (dwFlags  &  INTERNET_CONNECTION_PROXY)  ==  INTERNET_CONNECTION_PROXY  ?  INTERNET_OPEN_TYPE_PRECONFIG : INTERNET_OPEN_TYPE_PRECONFIG_WITH_NO_AUTOPROXY,
        NULL, NULL,  0 );
    AfxParseURL(m_strFileURL,dwFlags,strServer,strObject,nPort);

     if  (m_TimeOut  !=   0 )
        session.SetOption(INTERNET_OPTION_DATA_RECEIVE_TIMEOUT, m_TimeOut);
     if (  ! m_wFileID )
        m_wFileID  =  GenFileID();
    PostNotifyMessage(NOTIFY_MSG_WPARAM_GENDOWNFILEID,m_wFileID);

     try
    {
         if  ( dwFlags ==  AFX_INET_SERVICE_HTTP )
        {
            bRet  =  GetHttpFile(session);
        }
         else   if ( dwFlags ==  AFX_INET_SERVICE_FTP )
        {
            bRet  =  GetFtpFile(session);
        }
         else   if ( dwFlags ==  AFX_INET_SERVICE_FILE )
        {
             if ( UrlIsFileUrl(m_strFileURL) )
                bRet  =  GetUNCFile();
        }
         else
        {
            ;
        }    
    }
     catch  (CException *  pEx)
    {
        TCHAR szErrorMsg[MAX_PATH]  =  { 0 };
        pEx -> GetErrorMessage(szErrorMsg, MAX_PATH);
        TRACE( _T( " Exception: %s/n " ) , szErrorMsg);
        pEx -> Delete();
    }

    session.Close();
    m_wFileID  =   0 ;
     if  (bRet)
    {
         if  ( ! ::MoveFileEx(m_strTmpFileName,m_strSaveToFile,MOVEFILE_REPLACE_EXISTING) )
        {
            Sleep( 1000 );
            ::MoveFileEx(m_strTmpFileName,m_strSaveToFile,MOVEFILE_REPLACE_EXISTING);
        }
    }
     return  bRet;
}

BOOL CDownloadFile::GetHttpFile(CInternetSession  & cSession)
{
    BOOL bRet  =  FALSE;
    CFile m_TmpFile;
    CFileException fileException;
    
     if  (  ! m_TmpFile.Open (m_strTmpFileName, 
        CFile::modeCreate  |  CFile::modeNoTruncate   |  CFile::modeReadWrite
         |  CFile::shareDenyWrite     |  CFile::typeBinary,
         & fileException ) )
    {
        TRACE( _T( " Open File failed: %d/n " ), fileException.m_cause );
         return  bRet;
    }
    CString strRangeQuest;

     if  (m_TmpFile.GetLength() > 0 )
    {
        PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_CURRENTSIZE,m_wFileID),m_TmpFile.GetLength());
        m_TmpFile.SeekToEnd();
        strRangeQuest.Format( _T( " %sRange: bytes=%d-/r/n " ), szHeaders,m_TmpFile.GetLength());
    }
     else
        strRangeQuest  =  szHeaders;

    DWORD dwCount  =   0 ;
    CHttpFile *  pFile  =  NULL;
    CString strTmpURL  =  m_strFileURL;
     try
    {
        DWORD dwFlags  =  INTERNET_FLAG_TRANSFER_BINARY 
             | INTERNET_FLAG_DONT_CACHE
             | INTERNET_FLAG_PRAGMA_NOCACHE
            ;
         if  (m_bForceReload) {
            dwFlags  |=  INTERNET_FLAG_RELOAD;
        }
         // Here Find URLFile Redirect.
//         OpenRedirectHttpURL(strTmpURL,cSession);
        pFile  =  (CHttpFile * ) cSession.OpenURL(strTmpURL,  1 , dwFlags,strRangeQuest,  - 1 );
    }
     catch  (CInternetException *  e)
    {
        TCHAR   szCause[MAX_PATH]  =  { 0 };
        e -> GetErrorMessage(szCause, MAX_PATH);
        e -> Delete();
         delete  pFile;
        pFile  =  NULL;
         return  bRet;
    }
    
    COleDateTime startTime  =  COleDateTime::GetCurrentTime();
    DWORD dwHttpFileSize  =   0 ;
     if  (pFile)
    {
        BYTE buffer[BUFFER_SIZE + 1 ]  =  { 0 };
         try  {
            UINT nRead  =   0 ;
            pFile -> QueryInfo(HTTP_QUERY_CONTENT_LENGTH  |  HTTP_QUERY_FLAG_NUMBER,dwHttpFileSize);
            PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_FULLSIZE,m_wFileID),dwHttpFileSize);
            TRACE( _T( " Totoal Length is %d/n " ), dwHttpFileSize );
            dwCount  =   0 ;
             do
            {
                nRead  =  pFile -> Read(buffer, BUFFER_SIZE);
                 if  (nRead  >   0 )
                {
                    buffer[nRead]  =   0 ;
                    m_TmpFile.Write(buffer,nRead);
                    
                    COleDateTimeSpan elapsed  =  COleDateTime::GetCurrentTime()  -  startTime;
                     double  dSecs  =  elapsed.GetTotalSeconds();
                    PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSIZE,m_wFileID),dwCount);
                     if  (dSecs  >   0.0 )
                    {
                        dwCount  +=  nRead;
                        m_transferRate  =  ( float ) ( dwCount  /   1024.0   /  dSecs );
                        TRACE( " Read %d bytes (%0.1f Kb/s)/n " , dwCount, m_transferRate );
                    }
                     else
                    {
                        TRACE( " Read %d bytes/n " , dwCount);
                        m_transferRate  =  ( float ) ( dwCount  /   1024.0  );
                    }
                    PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSPEED,m_wFileID),(LPARAM)m_transferRate);
                }
            }
             while  (nRead  >   0 );
            bRet  =  TRUE;
        }
         catch  (CFileException  * e)
        {
            TCHAR   szCause[MAX_PATH]  =  { 0 };
            e -> GetErrorMessage(szCause, MAX_PATH);
            TRACE( " ErrorMsg : %s/n " , szCause);
            e -> Delete();
             delete  pFile;
            m_TmpFile.Close();
             return  FALSE;
        }
        pFile -> QueryInfoStatusCode(m_infoStatusCode);       
        pFile -> QueryInfo(HTTP_QUERY_RAW_HEADERS ,m_rawHeaders);
        pFile -> Close();
        m_TmpFile.Close();
         delete  pFile;
    }
    
     return  bRet;
}

BOOL CDownloadFile::OpenRedirectHttpURL(CString  & strOldLocation,CInternetSession  & cSession)
{
    BOOL bRet  =  FALSE;
    CHttpFile  * pFile  =  NULL;
    CHttpConnection *  pServer  =  NULL;
    CString strServerName,strObject;
    INTERNET_PORT nPort  =   0 ;
    DWORD dwServiceType  =   0 ;
    
     if  ( ! AfxParseURL(strOldLocation, dwServiceType, strServerName, strObject, nPort)  ||
        dwServiceType  !=  INTERNET_SERVICE_HTTP)
    {
        TRACE( _T( " Not A Http Quest!/n " ) );
         return  bRet;
    }
    
    pServer  =  cSession.GetHttpConnection(strServerName, nPort);
    
    pFile  =  pServer -> OpenRequest(CHttpConnection::HTTP_VERB_GET,
        strObject, NULL,  1 , NULL, NULL, 
        INTERNET_FLAG_EXISTING_CONNECT  |  INTERNET_FLAG_NO_AUTO_REDIRECT);
    pFile -> AddRequestHeaders(szHeaders);
    pFile -> SendRequest();
    
    DWORD dwRet;
    pFile -> QueryInfoStatusCode(dwRet);
    
     //  if access was denied, prompt the user for the password
    
     if  (dwRet  ==  HTTP_STATUS_DENIED)
    {
        DWORD dwPrompt;
        dwPrompt  =  pFile -> ErrorDlg(NULL, ERROR_INTERNET_INCORRECT_PASSWORD,
            FLAGS_ERROR_UI_FLAGS_GENERATE_DATA  |  FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS, NULL);
        
         //  if the user cancelled the dialog, bail out
        
         if  (dwPrompt  !=  ERROR_INTERNET_FORCE_RETRY)
        {
            TRACE( _T( " Access denied: Invalid password/n " ) );
             //  close up the redirected site

            pFile -> Close();
             delete  pFile;
            pServer -> Close();
             delete  pServer;

             return  bRet;
        }
        
        pFile -> SendRequest();
        pFile -> QueryInfoStatusCode(dwRet);
    }
        
     //  were we redirected?
     //  these response status codes come from WININET.H
    
     if  (dwRet  ==  HTTP_STATUS_MOVED  ||
        dwRet  ==  HTTP_STATUS_REDIRECT  ||
        dwRet  ==  HTTP_STATUS_REDIRECT_METHOD)
    {
        CString strNewLocation;
        pFile -> QueryInfo(HTTP_QUERY_RAW_HEADERS_CRLF, strNewLocation);
         int  nPlace  =  strNewLocation.Find(_T( " Location:  " ));
         if  (nPlace  ==   - 1 )
        {
            TRACE( _T( " Error: Site redirects with no new location/n " ) );
             //  close up the redirected site

            pFile -> Close();
             delete  pFile;
            pServer -> Close();
             delete  pServer;
             return  bRet;
        }    
        strNewLocation  =  strNewLocation.Mid(nPlace  +   10 );
        nPlace  =  strNewLocation.Find('/n');
         if  (nPlace  >   0 )
            strNewLocation  =  strNewLocation.Left(nPlace);
        strOldLocation  =  strNewLocation;
    }
     if  ( dwRet  ==  HTTP_STATUS_OK )
    {
        bRet  =  TRUE;
    }
     //  close up the redirected site
    pFile -> Close();
     delete  pFile;
    pServer -> Close();
     delete  pServer;

     return  bRet;
}

BOOL CDownloadFile::GetFtpFile(CInternetSession  & cSession)
{
    BOOL bRet  =  FALSE;
    CFile m_TmpFile;
    CFileException fileException;
    
     if  (  ! m_TmpFile.Open (m_strTmpFileName, 
        CFile::modeCreate  |  CFile::modeNoTruncate   |  CFile::modeReadWrite
         |  CFile::shareDenyWrite     |  CFile::typeBinary,
         & fileException ) )
    {
        TRACE( _T( " Open File failed: %d/n " ), fileException.m_cause );
         return  bRet;
    }

    DWORD dwCount  =   0 ;
    CFtpConnection  * pFtpConn  =  NULL;
    CInternetFile  * pFile  =  NULL;
     try
    {
        CString strServerName,strObject,strUserName,strPassword;
        INTERNET_PORT nPort  =   0 ;
        DWORD dwServiceType  =   0 ;
        CString strRestPointCommand;
    
         if  ( ! AfxParseURLEx(m_strFileURL, dwServiceType, strServerName, strObject, nPort, 
            strUserName, strPassword)  ||
            dwServiceType  !=  INTERNET_SERVICE_FTP)
        {
            TRACE( _T( " Not A Ftp Quest!/n " ) );
        }
         //  CFtpConnection ERROR_INTERNET_NO_DIRECT_ACCESS CInternetSession
         if  (strUserName.IsEmpty())
            pFtpConn  =  cSession.GetFtpConnection(strServerName,NULL,NULL,nPort,m_bForceReload);
         else
            pFtpConn  =  cSession.GetFtpConnection(strServerName,strUserName,strPassword,nPort,m_bForceReload);
         if  (m_TmpFile.GetLength())
        {
            PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_CURRENTSIZE,m_wFileID),m_TmpFile.GetLength());
            m_TmpFile.SeekToEnd();
            strRestPointCommand.Format( _T( " REST %d " ), m_TmpFile.GetLength());
             // strRestPointCommand.Format( _T("ls") );
             if  (  ! FtpCommand(( * pFtpConn), FALSE, FTP_TRANSFER_TYPE_ASCII, 
            strRestPointCommand,  0 ,  0 ) )
            {
                TRACE( _T( " FtpCommand failed, error: %d/n " ), GetLastError());
                m_TmpFile.SeekToBegin();
            }    
        }
         if  (pFtpConn)
        {
            pFile  =  pFtpConn -> OpenFile(strObject);
        }
    }
     catch  (CInternetException *  e)
    {
        TCHAR   szCause[MAX_PATH]  =  { 0 };
        e -> GetErrorMessage(szCause, MAX_PATH);
        e -> Delete();
         delete  pFile;
         delete  pFtpConn;
         return  bRet;
    }
    
    COleDateTime startTime  =  COleDateTime::GetCurrentTime();
    DWORD dwFtpFileSize  =   0 ;
     if  (pFile)
    {
        BYTE buffer[BUFFER_SIZE + 1 ]  =  { 0 };
         try  {
            UINT nRead  =   0 ;
            dwFtpFileSize  =  FtpGetFileSize( ( * pFile), 0 );
            PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_FULLSIZE,m_wFileID),dwFtpFileSize);
            TRACE( _T( " Totoal Length is %d/n " ), dwFtpFileSize );
            dwCount  =   0 ;
             do
            {
                nRead  =  pFile -> Read(buffer, BUFFER_SIZE);
                 if  (nRead  >   0 )
                {
                    buffer[nRead]  =   0 ;
                    m_TmpFile.Write(buffer,nRead);
                    
                    COleDateTimeSpan elapsed  =  COleDateTime::GetCurrentTime()  -  startTime;
                     double  dSecs  =  elapsed.GetTotalSeconds();
                    PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSIZE,m_wFileID),dwCount);
                     if  (dSecs  >   0.0 )
                    {
                        dwCount  +=  nRead;
                        m_transferRate  =  ( float )(dwCount  /   1024.0   /  dSecs);
                        TRACE( " Read %d bytes (%0.1f Kb/s)/n " , dwCount, m_transferRate );                    
                    }
                     else
                    {
                        TRACE( " Read %d bytes/n " , dwCount);
                        m_transferRate  =  ( float )(dwCount  /   1024.0 );
                    }
                    PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSPEED,m_wFileID),(LPARAM)m_transferRate);
                }
            }
             while  (nRead  >   0 );
            bRet  =  TRUE;
        }
         catch  (CFileException  * e)
        {
            TCHAR   szCause[MAX_PATH]  =  { 0 };
            e -> GetErrorMessage(szCause, MAX_PATH);
            TRACE( " ErrorMsg : %s/n " , szCause);
            e -> Delete();
             delete  pFile;
            pFtpConn -> Close();
             delete  pFtpConn;
            m_TmpFile.Close();
             return  FALSE;
        }
        pFile -> Close();
         delete  pFile;
        m_TmpFile.Close();
        pFtpConn -> Close();
         delete  pFtpConn;
    }
     return  bRet;
}

BOOL CDownloadFile::GetUNCFile()
{
    BOOL bRet  =  FALSE;
    CFile m_TmpFile,m_SrcFile;
    CFileException fileException;
    CString strOldLocation  =  m_strFileURL;
     if  (  ! m_TmpFile.Open (m_strTmpFileName, 
        CFile::modeCreate  |  CFile::modeNoTruncate   |  CFile::modeReadWrite
         |  CFile::shareDenyWrite     |  CFile::typeBinary,
         & fileException ) )
    {
        TRACE( _T( " Open File failed: %d/n " ), fileException.m_cause );
         return  bRet;
    }
    strOldLocation.TrimLeft();
    strOldLocation.TrimRight();
     if ( StrCmpNI(strOldLocation, _T( " file:/ " ), 6 )  ==   0  )
    {
        strOldLocation  =  strOldLocation.Mid( 8 );
        strOldLocation.Replace( _T(' / '), _T('//'));
    }

     if  (  ! m_SrcFile.Open ( strOldLocation, 
         CFile::modeRead  |  CFile::shareDenyWrite  |  CFile::typeBinary,
         & fileException ) )
    {
        TRACE( _T( " Open File failed: %d/n " ), fileException.m_cause );
         return  bRet;
    }
    COleDateTime startTime  =  COleDateTime::GetCurrentTime();
    DWORD dwCount  =   0 ;
     try  {
         if  (m_TmpFile.GetLength())
        {
            PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_CURRENTSIZE,m_wFileID),m_TmpFile.GetLength());
            m_TmpFile.SeekToEnd();
            m_SrcFile.Seek(m_TmpFile.GetLength(), CFile::begin);
        }
        BYTE buffer[BUFFER_SIZE + 1 ]  =  { 0 };
        UINT nRead  =   0 ;
        PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_FULLSIZE,m_wFileID),m_SrcFile.GetLength());
        TRACE( _T( " Totoal Length is %d,left is %d/n " ), m_SrcFile.GetLength() ,m_SrcFile.GetLength()  -  m_TmpFile.GetLength());
        dwCount  =   0 ;
         do
        {
            nRead  =  m_SrcFile.Read(buffer, BUFFER_SIZE);
             if  (nRead  >   0 )
            {
                buffer[nRead]  =   0 ;
                m_TmpFile.Write(buffer,nRead);
                
                COleDateTimeSpan elapsed  =  COleDateTime::GetCurrentTime()  -  startTime;
                 double  dSecs  =  elapsed.GetTotalSeconds();
                PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSIZE,m_wFileID),dwCount);
                 if  (dSecs  >   0.0 )
                {
                    dwCount  +=  nRead;
                    m_transferRate  =  ( float )(dwCount  /   1024.0   /  dSecs);
                    TRACE( " Read %d bytes (%0.1f Kb/s)/n " , dwCount, m_transferRate );                    
                }
                 else
                {
                    TRACE( " Read %d bytes/n " , dwCount);
                    m_transferRate  =  ( float )(dwCount  /   1024.0 );
                }
                PostNotifyMessage(MAKEWPARAM(NOTIFY_MSG_LOW_WPARAM_DOWNSPEED,m_wFileID),(LPARAM)m_transferRate);
            }
        }
         while  (nRead  >   0 );
        bRet  =  TRUE;
    }
     catch  (CFileException  * e)
    {
        TCHAR   szCause[MAX_PATH]  =  { 0 };
        e -> GetErrorMessage(szCause, MAX_PATH);
        TRACE( " ErrorMsg : %s/n " , szCause);
        e -> Delete();
        m_TmpFile.Close();
         return  FALSE;
    }
    m_TmpFile.Close();
     return  bRet;
}

 void  CDownloadFile::RegisterNotifyWindow(DWORD dwThreadID,HWND hWnd, DWORD dwMsg)
{
    m_dwThreadID  =  dwThreadID;
    m_hNotify  =  hWnd;
    m_dwMsgID  =  dwMsg;
}

 void  CDownloadFile::PostNotifyMessage(WPARAM wParam, LPARAM lParam)
{
     if  (m_hNotify)
    {
        ::PostMessage(m_hNotify, m_dwMsgID, wParam,  lParam);
    }
     if  ( m_dwThreadID )
    {
        ::PostThreadMessage(m_dwThreadID,m_dwMsgID, wParam, lParam);
    }
}

WORD CDownloadFile::GenFileID()
{
    srand(GetTickCount());
     return  rand()  &   0xFFFF ;
}
UINT ThreadDownSingleFile( LPVOID pParam )
{
    CDownloadFile m_DownFile;
    UINT uRet  =   0 ;
     if  (lpDownParam)
    {
        m_DownFile.m_wFileID  =  m_DownFile.GenFileID();
         // 这里注册通知窗口和消息
         // m_DownFile.RegisterNotifyWindow
         if  ( m_DownFile.DownLoadFile(m_Msg.lpFileSrc, m_Msg.lpFileDst) )
        {
            uRet  =   1 ;
        }
    }
     return  uRet;
}
 
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