关于Delphi中流的使用-压缩与解压缩的函数

关于 Delphi 中流的使用(8) 压缩与解压缩的函数 
//Zlib.pas
//类:TCompressionStream

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.