近7日数据

要获取近7日的数据，但是数据库查询出来的时候，缺少某日的数据。
如09-03到09-09，但数据库中没有09-07的数据，所以查询的数据缺失09-07相关数值，需要在代码层面填充。
mysql获取近7日的数据

SELECT SUM(cost) AS cost,
 DATE_FORMAT(time, '%Y-%m-%d') AS dateTime
FROM
	orders
WHERE
	DATE_SUB(CURDATE(), INTERVAL 6 DAY) <= date(time)
GROUP BY
	DATE_FORMAT(time, '%Y-%m-%d');

sql语句处理不了，在代码层处理——

1.用Calendar来处理日期数组

  /**
     * 获取过去任意天内的日期数组
     * @param intervals
     * @return
     */
    public static ArrayList<String> pastDaysList(int intervals) {
        ArrayList<String> pastDaysList = new ArrayList<>();
        for (int i = 0; i < intervals; i++) {
            pastDaysList.add(getPastDate(i));
        }
        return pastDaysList;
    }

    /**
     * 获取过去第几天的日期
     *
     * @param past
     * @return
     */
    public static String getPastDate(int past) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past);
        Date today = calendar.getTime();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        String result = format.format(today);
        return result;
    }

2.匹配日期并处理数值

 public Map<String, Object> toWeekIncome(String area) {
        List<Map<String, Object>> list = ordersDao.toWeekIncome(area);
        //LinkedHashMap保证顺序
        HashMap<String, Object> dayMap = new LinkedHashMap<>();
        //获取近7日内日期数组
        ArrayList<String> dateList = DateUtil.pastDaysList(7);
        for (int i = 0; i < dateList.size(); i++) {
            //初始化日期与数值
            dayMap.put(dateList.get(i).substring(5), 0.00);
            //循环匹配相关日期的数值
            for (int j = 0; j < list.size(); j++) {
                String s = dateList.get(i);
                String dateTime = list.get(j).get("dateTime").toString();
                if (s.equals(dateTime)) {
                    dayMap.put(dateList.get(i).substring(5), list.get(j).get("income"));
                }
            }
        }
        Map<String, Object> data = new HashMap<String, Object>();
        data.put("xAxis", dayMap.keySet());
        data.put("yAxis", dayMap.values());
        return data;
    }

接口获得数据格式