Solved

Downloading multiple images from URL FAST

Posted on 2007-11-27
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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
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Question by:ST3VO
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LVL 10

Expert Comment

by:dinilud
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LVL 10

Expert Comment

by:dinilud
Comment Utility
See rllibby's solution from the above link
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Author Comment

by:ST3VO
Comment Utility
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
Comment Utility
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!

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Author Comment

by:ST3VO
Comment Utility
Url's I've inserted in the listbox format are:

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

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Accepted Solution

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dinilud earned 500 total points
Comment Utility
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

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Author Comment

by:ST3VO
Comment Utility
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.

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LVL 10

Expert Comment

by:dinilud
Comment Utility
rllibby's this comonent is a mutithreaded component.
You check the updation of download list.
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Author Comment

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

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Author Comment

by:ST3VO
Comment Utility
Note: Without downloading any download acelerators ;o)
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LVL 10

Expert Comment

by:dinilud
Comment Utility
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LVL 10

Expert Comment

by:dinilud
Comment Utility
Check On progress events of that component.
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Author Comment

by:ST3VO
Comment Utility
UrlDownload1UrlProgress(Sender: TObject; ID,
  TotalSize: Cardinal; Stream: TStream); ???
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Author Comment

by:ST3VO
Comment Utility
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
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Author Comment

by:ST3VO
Comment Utility
Never mind. I've done it!!!

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