代码如下

/// <summary>
/// 复制流
/// </summary>
/// <param name="input">原始流</param>
/// <param name="output">目标流</param>
public static void CopyStream(System.IO.Stream input, System.IO.Stream output)
{
  byte[] buffer = new byte[2000];
  int len;
  while ((len = input.Read(buffer, 0, 2000)) > 0)
  {
    output.Write(buffer, 0, len);
  }
  output.Flush();
}
/// <summary>
/// 压缩字节数组
/// </summary>
/// <param name="sourceByte">需要被压缩的字节数组</param>
/// <returns>压缩后的字节数组</returns>
private static byte[] compressBytes(byte[] sourceByte)
{
  MemoryStream inputStream = new MemoryStream(sourceByte);
  Stream outStream = compressStream(inputStream);
  byte[] outPutByteArray = new byte[outStream.Length];
  outStream.Position = 0;
  outStream.Read(outPutByteArray, 0, outPutByteArray.Length);
  outStream.Close();
  inputStream.Close();
  return outPutByteArray;
}
/// <summary>
/// 解压缩字节数组
/// </summary>
/// <param name="sourceByte">需要被解压缩的字节数组</param>
/// <returns>解压后的字节数组</returns>
private static byte[] deCompressBytes(byte[] sourceByte)
{
  MemoryStream inputStream = new MemoryStream(sourceByte);
  Stream outputStream = deCompressStream(inputStream);
  byte[] outputBytes = new byte[outputStream.Length];
  outputStream.Position = 0;
  outputStream.Read(outputBytes, 0, outputBytes.Length);
  outputStream.Close();
  inputStream.Close();
  return outputBytes;
}
/// <summary>
/// 压缩流
/// </summary>
/// <param name="sourceStream">需要被压缩的流</param>
/// <returns>压缩后的流</returns>
private static Stream compressStream(Stream sourceStream)
{
  MemoryStream streamOut = new MemoryStream();
  ZOutputStream streamZOut = new ZOutputStream(streamOut, zlibConst.Z_DEFAULT_COMPRESSION);
  CopyStream(sourceStream, streamZOut);
  streamZOut.finish();
  return streamOut;
}
/// <summary>
/// 解压缩流
/// </summary>
/// <param name="sourceStream">需要被解压缩的流</param>
/// <returns>解压后的流</returns>
private static Stream deCompressStream(Stream sourceStream)
{
  MemoryStream outStream = new MemoryStream();
  ZOutputStream outZStream = new ZOutputStream(outStream);
  CopyStream(sourceStream, outZStream);
  outZStream.finish();
  return outStream;
}

zlib.NET库下载：http://www.componentace.com/zlib_.NET.htm