本例效果图:



代码文件:
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unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
ProgressBar1: TProgressBar;
procedure Button1Click(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
const
getPath = 'c:\temp\get.rar';
setPath = 'c:\temp\set.rar';
var
getStream,setStream: TFileStream;
num, n: Integer;
buf: PByte;
BufSize,block: Integer;
begin

if not FileExists(getPath) then
begin
ShowMessage('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 do
begin
Application.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.