c#如何解压缩数据文件(deflatestream方式解压缩文件)

String sourcefilename = FILETOBEUNCOMPRESsed;
Filestream sourcefile = File.OpenRead(sourcefilename);
Filestream destinationfile = File.Create(outputfilename);
DeflateStream compressionstream = new DeflateStream(sourcefile,CompressionMode.Decompress);
int sourcebyte = compressionstream.ReadByte();
while(sourcebyte != -1)
{
  destinationfile.WriteByte((byte)sourcebyte);
  sourcebyte = compressionstream.ReadByte();
}