code: public static String guessEncoding(byte[] content) {
          String encoding;
          try {
              encoding = guessEncodingByNutch(content);
          } catch (Exception ex) {
              return guessEncodingByMozilla(content);
          }
  
          if (encoding == null) {
              encoding = guessEncodingByMozilla(content);
              return encoding;
          } else {
              return encoding;
          }
      }
docs: 根据字节数组，猜测可能的字符集，如果检测失败，返回utf-8
  @param content 待检测的字节数组
  @return 可能的字符集，如果检测失败，返回utf-8