java獲取當月第一天時間、當月最后一天時間、上月第一天時間、上月最后一天時間

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

public class test {
    public static void main(String[] args) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        // 本月起始
        Calendar thisMonthFirstDateCal = Calendar.getInstance();
        thisMonthFirstDateCal.set(Calendar.DAY_OF_MONTH, 1);
        String thisMonthFirstTime = format.format(thisMonthFirstDateCal.getTime()) + " 00:00:00";
        System.out.println("本月起始:" + thisMonthFirstTime);

        // 本月末尾
        Calendar thisMonthEndDateCal = Calendar.getInstance();
        thisMonthEndDateCal.set(Calendar.DAY_OF_MONTH, thisMonthEndDateCal.getActualMaximum(Calendar.DAY_OF_MONTH));
        String thisMonthEndTime = format.format(thisMonthEndDateCal.getTime()) + " 23:59:59";
        System.out.println("本月末尾:" + thisMonthEndTime);

        // 上月起始
        Calendar lastMonthFirstDateCal = Calendar.getInstance();
        lastMonthFirstDateCal.add(Calendar.MONTH,-1);
        lastMonthFirstDateCal.set(Calendar.DAY_OF_MONTH, 1);
        String lastMonthFirstTime = format.format(lastMonthFirstDateCal.getTime()) + " 00:00:00";
        System.out.println("上月起始:" + lastMonthFirstTime);

        // 上月末尾
        Calendar lastMonthEndDateCal = Calendar.getInstance();
        lastMonthEndDateCal.add(Calendar.MONTH,-1);
        lastMonthEndDateCal.set(Calendar.DAY_OF_MONTH, lastMonthEndDateCal.getActualMaximum(Calendar.DAY_OF_MONTH));
        String lastMonthEndTime = format.format(lastMonthEndDateCal.getTime()) + " 23:59:59";
        System.out.println("上月末尾:" + lastMonthEndTime);
    }
}