Java获取上个月，这个月第一天和最后一天

 
    public static Map getLastoneMonthDay() {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Map map = new HashMap<>();
        // 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());
        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());
        System.out.println("上月末尾:" + lastMonthEndTime);
        map.put("beginDate", lastMonthFirstTime);
        map.put("endDate", lastMonthEndTime);
        return map;
    }

    
    public static Map getNowoneMonthDay() {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Map map = new HashMap<>();
        // 本月起始
        Calendar thisMonthFirstDateCal = Calendar.getInstance();
        thisMonthFirstDateCal.set(Calendar.DAY_OF_MONTH, 1);
        String thisMonthFirstTime = format.format(thisMonthFirstDateCal.getTime());
        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());
        System.out.println("本月末尾:" + thisMonthEndTime);

        map.put("beginDate", thisMonthFirstTime);
        map.put("endDate", thisMonthEndTime);
        return map;
    }