Solved

Downloading multiple images from URL FAST

Posted on 2007-11-27
15
254 Views
Last Modified: 2010-04-05
Hi expert,

I need to download a list of images from a URL's FAST!

I guess the faster's way is to use Threads?

If so, could someone please give me an example code?

Or if anyone knows a faster way...

Hope you can help

thanks

ST3VO
0
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Question by:ST3VO
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15 Comments
 
LVL 10

Expert Comment

by:dinilud
ID: 20357349
0
 
LVL 10

Expert Comment

by:dinilud
ID: 20357358
See rllibby's solution from the above link
0
 

Author Comment

by:ST3VO
ID: 20357426
Hmmm....I can compile it without errors but when I try to run the application nothing happens :o/

Any ideas why???
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Author Comment

by:ST3VO
ID: 20357569
OK...got it running....

But how do I get this code to actually download files from the urls???

It's downloading nothing although I've changed the links the url's that link to images!

0
 

Author Comment

by:ST3VO
ID: 20357594
Url's I've inserted in the listbox format are:

for example:
http://www.somesite.com/animage.gif

0
 
LVL 10

Accepted Solution

by:
dinilud earned 500 total points
ID: 20358109
please try this

Unit1.dfm
===========
 
object Form1: TForm1
  Left = 10
  Top = 101
  Width = 779
  Height = 479
  Caption = 'Form1'
  Color = clBtnFace
  Font.Charset = ANSI_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object ListView1: TListView
    Left = 212
    Top = 44
    Width = 545
    Height = 385
    Columns = <
      item
        Caption = 'URL'
        Width = 120
      end
      item
        Caption = 'Result'
        Width = 200
      end>
    TabOrder = 0
    ViewStyle = vsReport
  end
  object Button1: TButton
    Left = 8
    Top = 12
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 1
    OnClick = Button1Click
  end
  object ListBox1: TListBox
    Left = 8
    Top = 44
    Width = 197
    Height = 385
    ItemHeight = 13
    Items.Strings = (
      'http://coastalkarate.com/files/image/gallery/00.jpg'
      'http://coastalkarate.com/files/image/gallery/01.jpg'
      'http://coastalkarate.com/files/image/gallery/02.jpg'
      'http://coastalkarate.com/files/image/gallery/03.jpg'
      'http://coastalkarate.com/files/image/gallery/04.jpg'
      'http://coastalkarate.com/files/image/gallery/05.jpg'
      'http://coastalkarate.com/files/image/gallery/06.jpg'
      'http://coastalkarate.com/files/image/gallery/07.jpg'
      'http://coastalkarate.com/files/image/gallery/08.jpg'
      'http://coastalkarate.com/files/image/gallery/09.jpg'
      'http://coastalkarate.com/files/image/gallery/10.jpg'
      'http://coastalkarate.com/files/image/gallery/11.jpg'
      'http://coastalkarate.com/files/image/gallery/12.jpg'
      'http://coastalkarate.com/files/image/gallery/13.jpg'
      'http://coastalkarate.com/files/image/gallery/14.jpg'
      'http://coastalkarate.com/files/image/gallery/15.jpg'
      'http://coastalkarate.com/files/image/gallery/16.jpg')
    TabOrder = 2
  end
  object UrlDownload1: TUrlDownload
    OnUrlOpen = UrlDownload1UrlOpen
    OnUrlError = UrlDownload1UrlError
    OnUrlComplete = UrlDownload1UrlComplete
    UserAgent = 'TUrlDownload'
    Left = 156
    Top = 8
  end
end
 
 
Unit1.pas
===========
 
unit Unit1;
 
interface
 
// UrlDown can be obtained from my site @
//
//   http://users.adelphia.net/~rllibby/downloads/urldown.zip
//
uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls, UrlDown;
 
type
  TForm1            =  class(TForm)
     UrlDownload1:  TUrlDownload;
     ListView1:     TListView;
     Button1:       TButton;
     ListBox1:      TListBox;
     procedure      Button1Click(Sender: TObject);
     procedure      UrlDownload1UrlOpen(Sender: TObject; ID: Cardinal);
     procedure      UrlDownload1UrlError(Sender: TObject; ID, Error: Cardinal);
     procedure      UrlDownload1UrlComplete(Sender: TObject; ID, TotalMilliseconds: Cardinal; Stream: TStream);
    procedure FormCreate(Sender: TObject);
  private
     // Private declarations
     FDir:String;
     function GetFileName(Url:String):String;
  public
     // Public declarations
  end;
 
var
  Form1:            TForm1;
 
implementation
{$R *.DFM}
 
function TForm1.GetFileName(Url:String):String;
var i:Integer;
begin
  Result:=url;
  for i:=length(Url) downto 1 do
  begin
    if Url[i]='/' then
    begin
      Result:=copy(Url,i+1,length(Url));
      Break;
    end;
  end;
 
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var  liItem:        TListItem;
     dwIndex:       Integer;
begin
 
  // Walk all url's
  for dwIndex:=0 to Pred(Listbox1.Items.Count) do
  begin
     // Add list item
     liItem:=ListView1.Items.Add;
     // Set list item caption
     liItem.Caption:=Listbox1.Items[dwIndex];
     // Set subitem
     liItem.SubItems.Add('contacting server...');
     // Queue the request
     URLDownload1.OpenRequestEx(Listbox1.Items[dwIndex], nil, Pointer(liItem.Index));
  end;
 
end;
 
procedure TForm1.UrlDownload1UrlOpen(Sender: TObject; ID: Cardinal);
var  liItem:        TListItem;
begin
 
  // Get index from context pointer
  liItem:=ListView1.Items[Integer(URLDownload1.RequestContext[ID])];
 
  // Set subitems text
  liItem.SubItems[0]:='downloading contents...';
 
end;
 
procedure TForm1.UrlDownload1UrlError(Sender: TObject; ID, Error: Cardinal);
var  liItem:        TListItem;
begin
 
  // Get index from context pointer
  liItem:=ListView1.Items[Integer(URLDownload1.RequestContext[ID])];
 
  // Set subitems text
  liItem.SubItems[0]:=Format('failed to get URL data, error code (%d)', [Error]);
 
end;
 
procedure TForm1.UrlDownload1UrlComplete(Sender: TObject; ID, TotalMilliseconds: Cardinal; Stream: TStream);
var  liItem:        TListItem;
     f:String;
begin
 
  // Get index from context pointer
  liItem:=ListView1.Items[Integer(URLDownload1.RequestContext[ID])];
 
  // Resource protection
  try
     F:=FDir+GetFileName(liItem.Caption);
     TMemoryStream(Stream).SaveToFile(f);
     liItem.SubItems[0]:='Compleated';
  finally
  end;
 
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
   FDir:=IncludeTrailingPathDelimiter(ExtractFileDir(Application.ExeName))+'DownLoadedFiles\';
   if not DirectoryExists(FDir) then CreateDir(FDir);
end;
 
end.

Open in new window

0
 

Author Comment

by:ST3VO
ID: 20358381
Hi dinilud,

I installed your component and to downloads worked fine, BUT my problem is that I need to download using as many Threads as possible.

This component will download one at a time and I need Multiple threads so I can download as fast as possible.

0
 
LVL 10

Expert Comment

by:dinilud
ID: 20358499
rllibby's this comonent is a mutithreaded component.
You check the updation of download list.
0
 

Author Comment

by:ST3VO
ID: 20358585
I have checked and it's downloading one at a time. I really need speed in downloading above all!

0
 

Author Comment

by:ST3VO
ID: 20358595
Note: Without downloading any download acelerators ;o)
0
 
LVL 10

Expert Comment

by:dinilud
ID: 20358600
0
 
LVL 10

Expert Comment

by:dinilud
ID: 20358667
Check On progress events of that component.
0
 

Author Comment

by:ST3VO
ID: 20358720
UrlDownload1UrlProgress(Sender: TObject; ID,
  TotalSize: Cardinal; Stream: TStream); ???
0
 

Author Comment

by:ST3VO
ID: 20359913
Hi dinilud,

I am going to go for your answer and it does work great. There's just 1 thing I need to know...

How could I get the application to Terminate once the downloads are completed?

Thanks

ST3VO
0
 

Author Comment

by:ST3VO
ID: 20360939
Never mind. I've done it!!!

0

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