关于 Delphi 中流的使用(9) 分割与合并文件的函数

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Button2: TButton;

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



//分割文件的函数

{参数 1 是要分割的文件名; 参数 2 是要风格文件的大小, 单位是 KB}

{分割后的文件名扩展名用序号替换}

function SplitFile(const FileName: string; Size: Cardinal): Boolean;

var

  fStream: TFileStream;    {原始文件}

  toStream: TMemoryStream; {分文件}

  p,i: Integer;            {p 记录当前指针位置; i 记录这是第几个分的文件}

begin

  Result := False;



  Size := Size * 1024;     {把大小的单位转换为字节}



  fStream := TFileStream.Create(FileName, fmOpenRead);

  p := 0;

  i := 0;



  toStream := TMemoryStream.Create;



  while p < fStream.Size do

  begin

    toStream.Clear;        {清空上次数据}

    fStream.Position := p; {放好指针位置}



    if fStream.Size-p < Size then Size := fStream.Size-p; {最后一个时, 有多少算多少}



    toStream.CopyFrom(fStream, Size); {复制}

    toStream.SaveToFile(FileName + '.' + IntToStr(i));        {保存}

    Inc(i);

    p := p + Size;

  end;



  fStream.Free;

  toStream.Free;

  Result := True;

end;





//合并文件, 参数是其中一个分文件名

function MergeFile(const FileName: string): Boolean;

var

  ms: TMemoryStream; {读取分文件}

  fs: TFileStream;   {合并后的文件}

  path: string;

  i: Integer;

begin

  path := ChangeFileExt(FileName,''); {去掉序号扩展名}

  ShowMessage(path);

  i := 0;



  ms := TMemoryStream.Create;

  fs := TFileStream.Create(path, fmCreate);



  while FileExists(path + '.' + IntToStr(i)) do

  begin

    ms.LoadFromFile(path + '.' + IntToStr(i));

    fs.CopyFrom(ms, 0); {TFileStream 不需要 SetSize; 但如果用 TMemoryStream 就需要}

    Inc(i);

  end;



  ms.Free;

  fs.Free;

end;







//测试分割

procedure TForm1.Button1Click(Sender: TObject);

begin

  SplitFile('c:\temp\test.txt', 10);

end;



//测试合并

procedure TForm1.Button2Click(Sender: TObject);

begin

  MergeFile('c:\temp\test.txt.0');

end;



end.