获取当前日期、当月月初日期、月末日期

public static void main(String[] args) {
        // 获取当前年份、月份、日期
        Calendar cale = Calendar.getInstance();
        int year = cale.get(Calendar.YEAR);
        int month = cale.get(Calendar.MONTH) + 1;
        int day = cale.get(Calendar.DATE);
        int hour = cale.get(Calendar.HOUR_OF_DAY);
        int minute = cale.get(Calendar.MINUTE);
        int second = cale.get(Calendar.SECOND);
        int dow = cale.get(Calendar.DAY_OF_WEEK);
        int dom = cale.get(Calendar.DAY_OF_MONTH);
        int doy = cale.get(Calendar.DAY_OF_YEAR);

        System.out.println("Current Date: " + cale.getTime());
        System.out.println("Year: " + year);
        System.out.println("Month: " + month);
        System.out.println("Day: " + day);
        System.out.println("Hour: " + hour);
        System.out.println("Minute: " + minute);
        System.out.println("Second: " + second);
        System.out.println("Day of Week: " + dow);
        System.out.println("Day of Month: " + dom);
        System.out.println("Day of Year: " + doy);

        // 获取当月第一天和最后一天
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        String firstday, lastday;
        // 获取前月的第一天
        cale = Calendar.getInstance();
        cale.add(Calendar.MONTH, 0);
        cale.set(Calendar.DAY_OF_MONTH, 1);
        firstday = format.format(cale.getTime());
        // 获取前月的最后一天
        cale = Calendar.getInstance();
        cale.add(Calendar.MONTH, 1);
        cale.set(Calendar.DAY_OF_MONTH, 0);
        lastday = format.format(cale.getTime());
        System.out.println("本月第一天和最后一天分别是 ： " + firstday + " and " + lastday);
    }