private static void getWeekByDate(Date time) {  
  
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // 设置时间格式  
        Calendar cal = Calendar.getInstance();  
        cal.setTime(time);  
        // 判断要计算的日期是否是周日，如果是则减一天计算周六的，否则会出问题，计算到下一周去了  
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天  
        if (1 == dayWeek) {  
            cal.add(Calendar.DAY_OF_MONTH, -1);  
        }  
        System.out.println("要计算日期为:" + sdf.format(cal.getTime())); // 输出要计算日期  
        cal.setFirstDayOfWeek(Calendar.MONDAY);// 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一  
        int day = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天  
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);// 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值  
        String imptimeBegin = sdf.format(cal.getTime());  
        System.out.println("所在周星期一的日期：" + imptimeBegin);  
        cal.add(Calendar.DATE, 2);  
        String imptimeMi = sdf.format(cal.getTime());  
        System.out.println("所在周星期三的日期：" + imptimeMi);  
        cal.add(Calendar.DATE, 2);  
        String imptimeEnd = sdf.format(cal.getTime());  
        System.out.println("所在周星期五的日期：" + imptimeEnd);  
  
    }  

获取当前是周几

public static final String getWeekZhCN(Date d1){
        String weekDay = "";
        String[] weekDays = {"周日", "周一", "周二", "周三", "周四", "周五", "周六"};
        Calendar cal = Calendar.getInstance();
        cal.setTime(d1);
        int w = cal.get(Calendar.DAY_OF_WEEK) - 1;
        if (w < 0)
              w = 0;
        weekDay = weekDays[w];
        
        return weekDay;
    }

获取年月日

    public String getDate() {
        if (this.date== null) {
//          Date d1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(String.valu));//定义起始日期
            Date d1 = recieveTime;
//          SimpleDateFormat sdf0 = new SimpleDateFormat("yyyy");
            SimpleDateFormat sdf1 = new SimpleDateFormat("M");
            SimpleDateFormat sdf2= new SimpleDateFormat("d");
            String month = sdf1.format(d1);
            String day = sdf2.format(d1);
            this.date =month+"."+day; 
        }
        return date;

将日期的年月日意外时间，安置为00

 Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTime();