(Delphi ActiveX) Get Size of File on Web Server

Demonstrates how to send a HEAD request to fetch information about a file on a web server, which hopefully includes the Content-Length in the response header.

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;
contentLengthStr: WideString;

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://nodejs.org/dist/v10.16.1/node-v10.16.1-win-x64.zip');
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:

// Date: Thu, 01 Aug 2019 12:47:27 GMT
// Content-Type: application/zip
// Content-Length: 17457922
// Connection: keep-alive
// Set-Cookie: __cfduid=da5b78dcdd8171683c5a578eb9c9f88c81564663647; expires=Fri, 31-Jul-20 12:47:27 GMT; path=/; domain=.nodejs.org; HttpOnly
// Last-Modified: Wed, 31 Jul 2019 18:21:57 GMT
// ETag: "5d41dc45-10a6302"
// Accept-Ranges: bytes
// Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
// Server: cloudflare
// CF-RAY: 4ff7ebb32ac4e1e2-ORD

// Get the Content-Length header.
contentLengthStr := resp.GetHeaderField('Content-Length');
// If the header exists...
if (resp.LastMethodSuccess = 1) then
  begin
    Memo1.Lines.Add('Content-Length: ' + contentLengthStr);
    // Your application can convert the contentLengthStr to an integer and then use it....
  end;
end;