根据输入的日期 获得当前日期为周几

public static String getWeekOfDate(Date dt) {        String[] weekDays = {"周日", "周一", "周二", "周三", "周四", "周五", "周六"};        Calendar cal = Calendar.getInstance();        cal.setTime(dt);        int w = cal.get(Calendar.DAY_OF_WEEK) - 1;        if (w < 0)            w = 0;        return weekDays[w];    }