code: public static String convertByStyle(String str, Style style) {
          switch (style) {
              case camelhump:
                  return camelhumpToUnderline(str);
              case uppercase:
                  return str.toUpperCase();
              case lowercase:
                  return str.toLowerCase();
              case camelhumpAndLowercase:
                  return camelhumpToUnderline(str).toLowerCase();
              case camelhumpAndUppercase:
                  return camelhumpToUnderline(str).toUpperCase();
              case normal:
              default:
                  return str;
          }
      }
docs: 根据指定的样式进行转换
  
  @param str
  @param style
  @return