A class to download files from the net

• Download demo project - 21 Kb
• Download source files - 5.6 Kb

CWebGrab is a simple class that allows you to quickly and easily download files from the net. The class is merely a light wrapper for the MFC internet classes, and as such supports any protocol that the MFC classes support.

The class is extremely simple to use and has only one main function that you need to call: CWebGrab::GetFile. The syntax is:

BOOL GetFile(LPCTSTR szURL, CString& strBuffer, 
             LPCTSTR szAgentName = NULL, CWnd* pWnd = NULL);

Downloads a file from the given URL

• szURL is the URL
• strBuffer is a CString buffer that will hold the contents of the downloaded file
• szAgentName is the agent name you want to send to the website (may be NULL)
• pWnd is a status window. Status updates will be sent to this window using SetWindowText()

BOOL GetFileInfo(LPCTSTR  szURL, CString& strLastModified, DWORD& dwSize,
                 DWORD& dwServerError, LPCTSTR szAgentName = NULL, 
                 CWnd* pWnd = NULL);

(Added by Ravi Bhavnani) Retrieves the information about a file from the given URL

• szURL is the URL
• strLastModified is a CString buffer that will hold the last modified date of the file
• dwServerError will return any error codes that were raised.
• szAgentName is the agent name you want to send to the website (may be NULL)
• pWnd is a status window. Status updates will be sent to this window using SetWindowText()

Bryce Burrows kindly updated the code to include the following functions:

void SetUseProxy(bool use);

Sets whether or not to use a proxy

void SetProxyServer(LPCSTR server);

Sets the proxy server

void SetProxyPort(UINT port);

Sets the proxy port

void SetProxy(LPCSTR proxy, WORD port, bool use=true);

Sets the proxy information in one call

void SetForceReload (bool bForceReload)

Sets whether or not to force a reload when downloading a document. If a force reload is set the the document will not be a cached version.

void GetForceReload()

Gets whether or not to force a reload when downloading a document.

void SetTimeOut(DWORD timeOut);

Sets the timeout for the operation

double GetRate();

Retrieves the download rate in Kb/sec

SHORT GetErrorCode();
CString GetErrorMessage();

Get the error code and message (if any)

Example of use

#include "webgrab.h"


void CWebGrabberDlg::OnDownload() 
{
    CString strBuffer;
    CWebGrab grab;
    if (grab.GetFile("http://www.mysite.com/index.htm", // the url

                     strBuffer,                         // buffer for data

                     _T("WebGrab demo"),                // agent name

                     GetDlgItem(IDC_STATUS)))           // Plain ol' CStatic window

    {
        TRACE0("everything went OK\n")
    }
}

History

26 Jan 2002 - Bryce Burrows kindly added the proxy code.

16 Feb 2002 - Bryce Burrows source code update.

2 Mar 2002 - Ravi Bhavnani added a "force reload" option to ensure that the downloaded data is not read from the cache, plus Get/SetForceReload() functions.

17 Apr 2002 - Ravi Bhavnani added a GetFileInfo