public void Dispose()
{
if (_stream != null)
{
_stream.Close();
_stream = null;
}
_fileName = null;
_dataMap = null;
GC.SuppressFinalize(this);
}
void ReInitialize()
{
_dataMap = new DataMap();
_dataMap.AddFirst(new FileDataBlock(0, _stream.Length));
_totalLength = _stream.Length;
}