code: public static String getAstro(String birth) {
          if (!isDate(birth)) {
              birth = "2000" + birth;
          }
          if (!isDate(birth)) {
              return "";
          }
          int month = Integer.parseInt(birth.substring(birth.indexOf("-") + 1,
                                                       birth.lastIndexOf("-")));
          int day = Integer.parseInt(birth.substring(birth.lastIndexOf("-") + 1));
          String s = "魔羯水瓶双鱼牡羊金牛双子巨蟹狮子处女天秤天蝎射手魔羯";
          int[] arr = {20, 19, 21, 21, 21, 22, 23, 23, 23, 23, 22, 22};
          int start = month * 2 - (day < arr[month - 1] ? 2 : 0);
          return s.substring(start, start + 2) + "座";
      }
docs: 根据生日获取星座
  
  @param birth
  日期格式为YYYY-mm-dd
  @return 星座,单一字符