jave将时间分为多段查询

在jave代码中，有时候Mysql关联大数据查询异常慢，而且又要关联查询，譬如要查询截止到昨天的所有已经付款或者发货的订单生成一个报表，这个时间可以分时间段来查询，比较很好的解决

下面展示一些 内联代码片。

// A code block
    public static void main(String[] args)
    {
        Integer day = 1;
        
        for (int num = 1; num < 5; num++)
        {
            System.out.println(num);
            if (num == 1)
            {
                Calendar endOfDay = DateUtils.getEndOfDay();
                endOfDay.add(Calendar.DAY_OF_MONTH, -(day+14));
                System.out.println(DateUtils.timeToString(endOfDay));

            }
            else if (num == 2)
            {
                Calendar startOfDay2 = DateUtils.getStartOfDay();
                startOfDay2.add(Calendar.DAY_OF_MONTH, -(day+13));
                System.out.println(DateUtils.timeToString(startOfDay2));
                
                Calendar startOfDay3 = DateUtils.getEndOfDay();
                startOfDay3.add(Calendar.DAY_OF_MONTH, -(day+7));
                System.out.println(DateUtils.timeToString(startOfDay3));

            }
            else if (num == 3)
            {
                Calendar startOfDay4 = DateUtils.getStartOfDay();
                startOfDay4.add(Calendar.DAY_OF_MONTH, -(day+6));
                System.out.println(DateUtils.timeToString(startOfDay4));
                
                Calendar startOfDay5 = DateUtils.getEndOfDay();
                startOfDay5.add(Calendar.DAY_OF_MONTH, -(day+1));
                System.out.println(DateUtils.timeToString(startOfDay5));
                
            }
            else
            {
                Calendar startOfDay6 = DateUtils.getStartOfDay();
                startOfDay6.add(Calendar.DAY_OF_MONTH, -(day));
                System.out.println(DateUtils.timeToString(startOfDay6));
            }
        }
        }

// 输出的结果
1
2021-10-19 23:59:59
2
2021-10-20 00:00:00
2021-10-26 23:59:59
3
2021-10-27 00:00:00
2021-11-01 23:59:59
4
2021-11-02 00:00:00