根据日期判断星期几

    //基姆拉尔森计算公式根据日期判断星期几
    public static String  CalculateWeekDay(int y, int m, int d) {
        if (m == 1 || m == 2) {
            m += 12;
            y--;
        }
        int iWeek = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7;
        switch (iWeek) {
            case 0:
                return "周一";
            case 1:
                return "周二";
            case 2:
                return "周三";
            case 3:
                return "周四";
            case 4:
                return "周五";
            case 5:
                return "周六";
            case 6:
                return "周日";
        }
        return null;
    }