src/org/nutz/lang/Times.java
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