jdk8 Group statistics based on time

• 1. Group statistics by time
• 2. The time field is in yyyy-MM-dd HH:mm:ss format
• 3. Monthly statistics, no increase in the calculation

1. Statistical methods

Time method to month: parse_yyyyMM, statistical data by month
Time method to month: parse_yyyyMMdd, statistical data by day

   /**
     * 折线图统计(按月)
     * <P>
     *     1- 患者统计
     *     2- 出货统计
     * </P>
     * @param ybOrderPageVO
     * @return
     */
    private List<AdminHomeStatisticsVO.Statistics> getStatistics(List<YbOrderPageVO> ybOrderPageVO) {
        if (ybOrderPageVO.size() != 0) {
            Map<String, List<YbOrderPageVO>> groupByMonth = ybOrderPageVO.stream().collect(
                    Collectors.groupingBy(o -> LocalDateTimeUtil.parse_yyyyMM(o.getCreateTime()))
            );
            List<AdminHomeStatisticsVO.Statistics> patientList = new ArrayList<>();
            groupByMonth.forEach((k, v) -> {
                patientList.add(new AdminHomeStatisticsVO.Statistics(k, v.size()));
            });
            return patientList;
        }
        return null;
    }

2. parse_yyyyMMdd method (to date)

    /**
     * 年月日时间处理
     * @param time
     * @return
     */
    public static String parse_yyyyMMdd(LocalDateTime time) {
        DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        return df.format(time);
    }

3. parse_yyyyMM method (to month)

    /**
     * 年月日时间处理
     * @param time
     * @return
     */
    public static String parse_yyyyMM(LocalDateTime time) {
        DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM");
        return df.format(time);
    }

4. Example of a line chart

• Personal open source project (universal background management system) –> https://gitee.com/wslxm/spring-boot-plus2 , you can check it out if you like

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