code: public static String underlineToCamelhump(String str) {
          Matcher matcher = UNDERLINE_TO_CAMELHUMP_PATTERN.matcher(str);
          StringBuilder builder = new StringBuilder(str);
          for (int i = 0; matcher.find(); i++) {
              builder.replace(matcher.start() - i, matcher.end() - i, matcher.group().substring(1).toUpperCase());
          }
          if (Character.isUpperCase(builder.charAt(0))) {
              builder.replace(0, 1, String.valueOf(Character.toLowerCase(builder.charAt(0))));
          }
          return builder.toString();
      }
docs: 将下划线风格替换为驼峰风格