Stop the indy Get() function

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4 total messages Started by bar Wed, 26 Mar 2008 17:24

#364

Author: bar
Date: Wed, 26 Mar 2008 17:24

31 lines
1780 bytes

Hi All,

If i am calling HTTP->Get(); in main GUI thread and placed TldAntiFreeze 
component on the form.
I have a pop-up menu on the form. Each menu item call the following function 
to download the .bmp file from the webserver.

void TfrmMain::DownloadFile(String URL)
{
    try
    {
        ErrFile = "";

        AnsiString FileName = "SomeFileName.bmp";
        std::auto_ptr<TFileStream> strm(new TFileStream(FileName,fmCreate));

        HTTP->Request->Pragma = "no-cache";
        HTTP->HandleRedirects = true;
        HTTP->ReadTimeout = 15000;

        HTTP->Get(URL, strm.get());
    }
    catch(const Exception &E)
    {
        ErrFile = E.Message;
    }

1.I am download a file of 1MB, the process is in progress. I want to set an 
option if another menu item is selected while downloading. I want to cancel 
the previous download completely, without raising the exception or giving my 
own message.

Re: Stop the indy Get() function

#365

Author: Remy Lebeau (TeamB)
Date: Wed, 26 Mar 2008 17:49

18 lines
1766 bytes

"bar" <shaikakbar250281@yahoo.co.in> wrote in message 
news:47ea86a8@newsgroups.borland.com...

> I want to cancel the previous download completely,
> without raising the exception

There is no way to do that.  The only way to abort the Get() is to either 
Disconnect() the connection, or raise an Exception in the OnWork event(s). 
Either one will cause an Exception to escape from Get() into your code, so 
you must handle it accordingly.  If you don't want to show an error message, 
then you will have to either check the Exception class type and ignore those 
you know are "safe".  Or better, just set a flag somewhere indicating that 
you caused an intentional exception, and then ignore the error in your 
exception handler.


Gambit

Re: Stop the indy Get() function

#371

Author: bar
Date: Thu, 27 Mar 2008 08:50

9 lines
1198 bytes

Hi Remy thanks for answering.

The function i shown has a problem,
Even when the file is not present at the server or if any kind of exception 
raises.
Still the file is creating with 0 bytes. How to avoid this, i  mean create 
the file only if the download success.

<g>

Re: Stop the indy Get() function

#372

Author: Remy Lebeau (TeamB)
Date: Thu, 27 Mar 2008 09:41

49 lines
2411 bytes

"bar" <shaikakbar250281@yahoo.co.in> wrote in message 
news:47eb5fc5@newsgroups.borland.com...

> Even when the file is not present at the server or if any
> kind of exception raises. Still the file is creating with 0 bytes.

That is because you are not deleting the file if the download fails.

> How to avoid this, i  mean create the file only if the download success.

You have to create the file first before starting the download, or else you 
won't have anything to download into (unless you download to memory first, 
and then save it to file afterwards).  If the download fails, simply delete 
the file, for example:

    void TfrmMain::DownloadFile(String URL)
    {
        ErrFile = "";
        try
        {
            String FileName = "SomeFileName.bmp";

            try
            {
                std::auto_ptr<TFileStream> strm(new TFileStream(FileName, 
fmCreate));

                HTTP->Request->Pragma = "no-cache";
                HTTP->HandleRedirects = true;
                HTTP->ReadTimeout = 15000;

                HTTP->Get(URL, strm.get());
            }
            catch(const Exception &E)
            {
                if( !E.InheritsFrom(__classid(EFCreateError)) )
                    DeleteFile(FileName);
                throw;
            }
        }
        catch(const Exception &E)
        {
            ErrFile = E.Message;
        }
    }


Gambit

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