Lazarus Pascal

Fetch Web Pages from Local Cache

See more HTTP Examples

Demonstrates how to keep a local cache to avoid re-fetching web pages. Lazarus Pascal

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Http;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  http: THttp;
  html: string;

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

  http := THttp.Create;

  //  Define a cache directory and set the number of levels based on the anticipated size of the cache.
  http.AddCacheRoot('c:/example/httpCache/');

  //  up to 256 sub-directories under the cache root will be created as needed to hold cached GET's.
  http.NumCacheLevels := 1;

  //  Tell the http object to fetch from the cache if possible.
  http.FetchFromCache := True;

  //  Also tell the http object to update the cache with newly fetched pages.
  http.UpdateCache := True;

  //  This HTTP GET should result in a cache file getting created.
  html := http.QuickGetStr('https://www.google.com/');
  if (http.LastMethodSuccess = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  //  The 1st GET was not from cache:
  WriteLn('Fetched from cache: ' + http.LastFromCache);

  //  Fetching again will cause the page to be delivered from our local cache.
  html := http.QuickGetStr('https://www.google.com/');
  if (http.LastMethodSuccess = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  //  The 2nd GET is from cache:
  WriteLn('Fetched from cache: ' + http.LastFromCache);


  http.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.