@Override public void write(byte[] buffer,int off,int nbytes) throws IOException {
  super.write(buffer,off,nbytes);
  crc.update(buffer,off,nbytes);
}

@ Override public void write ( byte [ ] buffer , int off , int nbytes ) throws IOException { super . write ( buffer , off , nbytes ) ; crc . update ( buffer , off , nbytes ) ; }
write up to nbytes of data from the given buffer , starting at offset off , to the underlying stream in gzip format .
