日期相差

1.日期处理

1.1 引入必要依赖:版本5.3.8

	<dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>${hutool.version}</version>
        </dependency>
	<dependency>
		<artifactId>hutool-core</artifactId>
		<groupId>cn.hutool</groupId>
		<version>${hutool.version}</version>
	<dependency>

2.1 指定日期格式转换

	DateTime date = DateUtil.date(Calendar.getInstance());
        String format = "yyyy-MM-dd HH:mm";
        String d = DateUtil.format(date, format);
        System.out.println("d = " + d);

2.2 指定增加n天后的日期

 String time = "2020-02-13";

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

        Date date = null;
        try {
            date = sdf.parse(time);
            Calendar calendar  =   Calendar.getInstance();
            calendar.setTime(date); //date放到Calender对象中
            calendar.add(Calendar.DATE, 7);//后增加n天
            Date result = calendar.getTime();
            String format = sdf.format(result);
            System.out.println("date = " + format);

        } catch (Exception e) {

            e.printStackTrace();

        }

2.3 判断二个日期之间相差几天 相差几年，相差几月

LocalDateTime currentTime = LocalDateTime.now();
        DateTimeFormatter df2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        String aa = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());

        LocalDateTime collectTimeDate2 = LocalDateTime.parse(aa,df2);
        //判断相差多少天 相差几年，相差几月，相差几天 （四舍五入后的效果）
        long between = ChronoUnit.MONTHS.between(collectTimeDate2, currentTime);
        System.out.println(between);