简单日期转化器，能自动识别闰年还是平年，对输入的年月日可以转换为一年的第几天，输入的天数可以自动转换成一年中的具体日期。-Simple date converter that can automatically identify a leap year or leap year, the input can be converted to year, month, day of the first few days, the number of days to enter Automatic