流的压缩和解压

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;