问题来源: http://www.cnblogs.com/del/archive/2008/12/02/1066817.html#1389078

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本例效果图:

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代码文件:

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unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls, ComCtrls;typeTForm1 = class(TForm)Button1: TButton;ProgressBar1: TProgressBar;procedure Button1Click(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
constgetPath = 'c:\temp\get.rar';setPath = 'c:\temp\set.rar';
vargetStream,setStream: TFileStream;num, n: Integer;buf: PByte;BufSize,block: Integer;
beginif not FileExists(getPath) thenbeginShowMessage('源文件不存在');Exit;end;getStream := TFileStream.Create(getPath, fmOpenRead or fmShareExclusive);setStream := TFileStream.Create(setPath, fmCreate);num := getStream.Size;setStream.Size := num;getStream.Position := 0;setStream.Position := 0;BufSize := num;block := BufSize div 100;GetMem(buf, BufSize);ProgressBar1.Max := 100;ProgressBar1.Min := 0;ProgressBar1.Position := 0;while num <> 0 dobeginApplication.ProcessMessages;n := block;if n > num then n := num;getStream.ReadBuffer(buf^, n);setStream.WriteBuffer(buf^, n);ProgressBar1.Position := Trunc((1 - num / BufSize) * 100);Dec(num, n);end;FreeMem(buf, BufSize);getStream.Free;setStream.Free;ShowMessage('复制完毕');ProgressBar1.Position := 0;
end;end.

窗体文件:

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object Form1: TForm1Left = 0Top = 0Caption = 'Form1'ClientHeight = 104ClientWidth = 265Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalsePosition = poDesktopCenterPixelsPerInch = 96TextHeight = 13object Button1: TButtonLeft = 96Top = 56Width = 75Height = 25Caption = 'Button1'TabOrder = 0OnClick = Button1Clickendobject ProgressBar1: TProgressBarLeft = 8Top = 16Width = 249Height = 17TabOrder = 1end
end