(Delphi ActiveX) Get the Last-Modified Date Before HTTP Download

Demonstrates how to send a HEAD request to get the last-modified date of a file on a web server (without downloading the file).

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: TChilkatHttp;
resp: IChilkatHttpResponse;
lastModStr: WideString;
ckdt: TCkDateTime;
dt: IDtObj;

begin
// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

http := TChilkatHttp.Create(Self);

resp := http.GetHead('https://www.chilkatsoft.com/hamlet.xml');
if (http.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

// Examine the response header.
Memo1.Lines.Add(resp.Header);

// Here is a sample response header:

// 	Content-Length: 279658
// 	Content-Type: text/xml
// 	Last-Modified: Thu, 12 May 2016 15:14:08 GMT
// 	Accept-Ranges: bytes
// 	ETag: "c1cd8bee60acd11:0"
// 	Server: Microsoft-IIS/8.5
// 	X-Powered-By: ASP.NET
// 	X-Powered-By-Plesk: PleskWin
// 	Date: Thu, 25 Jul 2019 16:40:54 GMT

// Get the Last-Modified header.
lastModStr := resp.GetHeaderField('Last-Modified');
// If the header exists...
if (resp.LastMethodSuccess = 1) then
  begin
    // Parse the RFC822 format date/time string
    ckdt := TCkDateTime.Create(Self);
    ckdt.SetFromRfc822(lastModStr);

    // If we want to access individual date/time parts (in the local timezone)
    dt := ckdt.GetDtObj(1);
    Memo1.Lines.Add('day/month/year = ' + IntToStr(dt.Day) + '/' + IntToStr(dt.Month) + '/' + IntToStr(dt.Year));

  end;
end;