Delphi用TActionList下载文件

TActionList有个标准动作TDownLoadURL，内部是使用的URLDownloadToFile，它下载文件时会定时产生OnDownloadProgress 事件，这样就可以用进度条显示：

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, ExtActns, ActnList, StdCtrls, ComCtrls;

type

  TForm1 = class(TForm)

    Button1: TButton;

    ActionList1: TActionList;

    ProgressBar1: TProgressBar;

    procedure Button1Click(Sender: TObject);

  private

    { Private declarations }

    procedure URL_OnDownloadProgress

              (Sender: TDownLoadURL;

              Progress, ProgressMax: Cardinal;

              StatusCode: TURLDownloadStatus;

              StatusText: String; var Cancel: Boolean) ;

  public

    { Public declarations }

  end;

var

  Form1: TForm1;

implementation

{$R *.dfm}

procedure Tform1.URL_OnDownloadProgress;

begin

   ProgressBar1.Max:= ProgressMax;

   ProgressBar1.Position:= Progress;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

   with TDownloadURL.Create(self) do

   try

     URL:='http://static.cnblogs.com/images/logo_small.gif';

     FileName := 'logo.jpg';

     OnDownloadProgress := URL_OnDownloadProgress;

     ExecuteTarget(nil) ;

   finally

     Free;

   end;

   showMessage('OK');

   ProgressBar1.Max := 0;

end;