Delphi用TActionList实现下载文件的方法

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:='//www.VeVB.COm/images/logo.gif';   FileName := 'logo.gif';   OnDownloadProgress := URL_OnDownloadProgress;   ExecuteTarget(nil) ;  finally   Free;  end;  showMessage('OK');  ProgressBar1.Max := 0;end;