public static Date getDateByNum(int day) {
        GregorianCalendar gd = new GregorianCalendar(1900, 1, 1);
        Date date = gd.getTime();
        date = nextDay(date, day);
        return date;
    }
public static Date getDateByNum(int day) {
        GregorianCalendar gd = new GregorianCalendar(1900, 1, 1);
        Date date = gd.getTime();
        date = nextDay(date, day);
        return date;
    }
public static Date getDateByNum ( int day ) { GregorianCalendar gd = new GregorianCalendar ( 1900 , 1 , 1 ) ; Date date = gd . getTime ( ) ; date = nextDay ( date , day ) ; return date ; }
getDayNum的逆方法(用于处理Excel取出的日期格式数据等)

@param day
天数
@return 反推出的时间
getDayNum的逆方法 ( 用于处理Excel取出的日期格式数据等 )