关于 Delphi 中流的使用(8) 压缩与解压缩的函数

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}



uses Zlib;



//压缩函数

procedure Zip(var fs: TMemoryStream);

var

  cs: TCompressionStream;

  ms: TMemoryStream;

  num: Integer;

begin

  if not(Assigned(fs) and (fs.Size>0)) then Exit;



    num := fs.Size;

    ms := TMemoryStream.Create;

    cs := TCompressionStream.Create(clMax, ms);

  try

    fs.SaveToStream(cs);

    cs.Free;

    //ms.Position := 0;

    fs.Clear;

    fs.WriteBuffer(num, sizeof(num));

    fs.CopyFrom(ms, 0);

  finally

    ms.Free;

  end;

end;



//解压函数

procedure UnZip(var fs: Tmemorystream);

var

  ds: TDecompressionStream;

  ms: TMemoryStream;

  num: Integer;

begin

  if not(Assigned(fs) and (fs.Size>0)) then Exit;



  fs.Position := 0;

  fs.ReadBuffer(num,sizeof(num));

  ms := TMemoryStream.Create;

  ds := TDecompressionStream.Create(fs);

  try

    ms.SetSize(num);

    ds.Read(ms.Memory^, num);

    //ms.Position := 0;

    fs.Clear;

    fs.CopyFrom(ms, 0);

  finally

    ds.Free;

    ms.Free;

  end;

end;





//压缩测试

procedure TForm1.Button1Click(Sender: TObject);

var

  ms: TMemoryStream;

begin

  ms := TMemoryStream.Create;

  ms.LoadFromFile('c:\temp\test.txt');

  Zip(ms);

  ms.SaveToFile('c:\temp\test.zipx');

end;



//解压测试

procedure TForm1.Button2Click(Sender: TObject);

var

  ms: TMemoryStream;

begin

  ms := TMemoryStream.Create;

  ms.LoadFromFile('c:\temp\test.zipx');

  UnZip(ms);

  ms.SaveToFile('c:\temp\test2.txt');

end;



end.