Delphi中的TActionList有個標準動作TDownLoadURL,內部是使用的URLDownloadToFile,它下載文件時會定時產生OnDownloadProgress 事件,這樣就可以用進度條顯示。
本文講述了Delphi用TActionList實現下載文件的方法,實現代碼如下所示:
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:='//www.companysz.com/images/logo.gif'; FileName := 'logo.gif'; OnDownloadProgress := URL_OnDownloadProgress; ExecuteTarget(nil) ; finally Free; end; showMessage('OK'); ProgressBar1.Max := 0;end;
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