code: public static void compress(InputStream is, OutputStream os) throws Exception {
  		GZIPOutputStream gos = new GZIPOutputStream(os);
  		int count;
  		byte data[] = new byte[BUFFER];
  		while ((count = is.read(data, 0, BUFFER)) != -1) {
  			gos.write(data, 0, count);
  		}
  		gos.finish();
  		gos.flush();
  		gos.close();
  	}
docs: 数据压缩
  @param is
  @param os
  @throws Exception