1、獲取本周的周一到周日

 //通過調整日歷，獲得本天所屬周的周一和周日
 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
 Calendar cal=new GregorianCalendar();
 cal.setFirstDayOfWeek(Calendar.MONDAY);
 cal.setTime(new Date());
 cal.set(Calendar.DAY_OF_WEEK, cal.getFirstDayOfWeek());
 String startTime1 = sdf.format(cal.getTime());
 cal.set(Calendar.DATE, cal.get(cal.DATE) 
 
+ 6);  
 String endTime1 = sdf.format(cal.getTime());
 date = startTime1+"~"+endTime1;

2、根據本周的時間獲得上周的周一和周日Calendar calendar = Calendar.getInstance();

　　Calendar calendar = Calendar.getInstance();

calendar.setTime(startTime);//startTime當前查詢周的周一（不一定是本周，也可以是指定查詢某一天的周一） 
calendar.set(Calendar.DATE, calendar.get(calendar.DATE) 
 
-1); 
end2 = sdf.parse(sdf.format(calendar.getTime()));
calendar.set(Calendar.DATE, calendar.get(calendar.DATE) -6);
start2 = sdf.parse(sdf.format(calendar.getTime()));

3、按照查詢的某周的周一到周日獲取指定周的周數據

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            //遍歷日期來查詢，保證一天一查，查詢結果是對的
            Calendar c = Calendar.getInstance();
            c.setTime(startTime);
            Date time 
 
= sdf.parse(sdf.format(c.getTime()));
            while(time.getTime()<=endTime.getTime())
            {
                //不是今天
                if(time.getTime()!=sdf.parse(sdf.format(new Date())).getTime())
                {
                    SalesOrderStatDay dayObj = salesOrderStatDayDAO.getDataByDate(userId,time);
                    list.add(dayObj);
                }
                else
                {
                    //統計一下今天的報單數據，因為後臺數據是使用quartz定時任務在零點才去統計當天數據，為了能看到當天數據 只能去實時查詢
                    SalesOrderStatDay dayObj = getTodayData(userId);
                    list.add(dayObj);
                }
                c.add(Calendar.DATE, 1);
                time = sdf.parse(sdf.format(c.getTime()));//從周一加到周日
                
                
            }

4、獲取指定月份

sdf= new SimpleDateFormat("yyyy-MM");
            Calendar calendar = Calendar.getInstance();
            try {
                calendar.setTime(sdf.parse(month));
            } catch (ParseException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            calendar.set(calendar.MONTH, calendar.get(calendar.MONTH) -1);//進行減一操作，因為系統計算月份是從0開始
            date2 = sdf.format(calendar.getTime());

5、按照月份查詢每一天數據

SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM");
            SimpleDateFormat sdflll= new SimpleDateFormat("yyyy-MM-dd");
            Date today = sdflll.parse(sdflll.format(new Date()));
            Calendar cal = Calendar.getInstance();
            cal.setTime(sdf.parse(date));
            //總天數
            int dayNum = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
            cal.set(Calendar.DAY_OF_MONTH,1);
            for(int i=1;i<=dayNum;i++)
            {
                Date time = sdflll.parse(sdflll.format(cal.getTime()));
                //不是今天
                if(cal.getTime()!=today.getTime())
                {
                    SalesOrderStatDay dayObj = salesOrderStatDayDAO.getDataByDate(userId,time);
                    list.add(dayObj);
                }
                else
                {
                    //統計一下今天的報單數據
                    SalesOrderStatDay dayObj = getTodayData(userId);
                    list.add(dayObj);
                }
                cal.add(Calendar.DATE, 1);//日期加一
                
            }

關於Java類Calendar做統計時 獲取日期的一些常見操作