• 复制文件时,如何显示进度条(使用TFileStream一点一点读,或者使用BlockRead,并插入application.ProcessMessages)


    procedure mycopyfile(sourcef,targetf:string;i:integer);
    var
           FromF,ToF:file;
           NumRead,NumWritten:Integer;
           Buf:array[1..2048] of Char;
           n:integer;
    begin
             AssignFile(FromF,sourcef);
             Reset(FromF,    1); {    Record    size    =    1    }
             AssignFile(ToF,targetf); {    Open    output    file    }
             Rewrite(ToF,    1); {    Record    size    =    1    }
             n:=0;   
             repeat
                       BlockRead(FromF,    Buf,    SizeOf(Buf),    NumRead);
                       form1.ProgressBar1.Position:=sizeof(buf)*n*100    div    FileSize(FromF)*i div 4;
                       application.ProcessMessages;
                       //显示进度
                       BlockWrite(ToF,    Buf,    NumRead,    NumWritten);
                       inc(n);
               until    (NumRead    =    0)    or    (NumWritten    <>    NumRead);
               form1.ProgressBar1.Position:=100;
               CloseFile(FromF);
               CloseFile(ToF);
    end; 

    完整代码:

    以下例子是关于delphi复制文件,加上进度条的方法的例子的关键代码:
    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.

    http://blog.csdn.net/shuaihj/article/details/6129551

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  • 原文地址:https://www.cnblogs.com/findumars/p/5346061.html
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