code: private static void compressGZip(Resource source, Resource target) throws IOException {
  	if (source.isDirectory()) {
  	    throw new IOException("you can only create a GZIP File from a single source file, use TGZ (TAR-GZIP) to first TAR multiple files");
  	}
  	InputStream is = null;
  	OutputStream os = null;
  	try {
  	    is = source.getInputStream();
  	    os = target.getOutputStream();
  	}
  	catch (IOException ioe) {
  	    IOUtil.closeEL(is, os);
  	    throw ioe;
  	}
  	compressGZip(is, os);
  
      }
docs: compress a source file to a gzip file
  
  @param source
  @param target
  @throws IOException
  @throws IOException