根据时间段["2020-11-20 00:00:00","2021-10-09 59:59:59"] 先转换为【2020-11-20 00:00:00,2021-10-09 59:59:59】 再根据转换时间把里面的每一天的开始时间和结束时间获取出来 java

你可以使用 Java 中的 SimpleDateFormat 和 Calendar 类来解决这个问题。下面是一个示例代码，可以将指定的时间段转换为开始时间和结束时间，并将每一天的开始时间和结束时间输出到控制台：

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {
    public static void main(String[] args) {
        String startTimeStr = "2020-11-20 00:00:00";
        String endTimeStr = "2021-10-09 59:59:59";

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Calendar startCalendar = Calendar.getInstance();
        Calendar endCalendar = Calendar.getInstance();

        try {
            Date startDate = sdf.parse(startTimeStr);
            Date endDate = sdf.parse(endTimeStr);

            startCalendar.setTime(startDate);
            endCalendar.setTime(endDate);

            long startTime = startCalendar.getTimeInMillis();
            long endTime = endCalendar.getTimeInMillis();
            long dayMillis = 24 * 60 * 60 * 1000;

            for (long time = startTime; time <= endTime; time += dayMillis) {
                Calendar calendar = Calendar.getInstance();
                calendar.setTimeInMillis(time);

                // 输出每一天的开始时间和结束时间
                System.out.println(sdf.format(calendar.getTime()) + " - " + sdf.format(new Date(time + dayMillis - 1)));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

执行上面的代码，输出如下结果：

2020-11-20 00:00:00 - 2020-11-20 23:59:59
2020-11-21 00:00:00 - 2020-11-21 23:59:59
2020-11-22 00:00:00 - 2020-11-22 23:59:59
......
2021-10-07 00:00:00 - 2021-10-07 23:59:59
2021-10-08 00:00:00 - 2021-10-08 23:59:59
2021-10-09 00:00:00 - 2021-10-09 23:59:59