JAVA日期相关操作

news2024/12/25 12:12:54

JAVA日期相关操作

计算两个日期相差的天数

    /**
     * 计算两个日期相差的  天数
     * @param smdate String类型初始时间
     * @param bdate  String类型截至时间
     * @return Integer
     */
    public static Integer dayCompare(String smdate, String bdate) throws Exception {
        Date start = sdf.parse(smdate);
        Date end = sdf.parse(bdate);
        Calendar cal = Calendar.getInstance();
        cal.setTime(start);
        long time1 = cal.getTimeInMillis();
        cal.setTime(end);
        long time2 = cal.getTimeInMillis();
        long between_days = (time2 - time1) / (1000 * 3600 * 24);
        return Integer.parseInt(String.valueOf(between_days));
    }

计算两个日期之间的所有日期

   /**
     * @param startDay 开始时间
     * @param endDay   结束时间
     * @return List<String>
     * @author bigfaceYang
     * 获取两个日期之间天数
     * @date 2021/11/11 16:09
     */
    public static List<String> getDays(String startDay, String endDay) throws Exception {
        List<String> list = new ArrayList<>();
        Calendar min = Calendar.getInstance();
        Calendar max = Calendar.getInstance();
        min.setTime(sdf.parse(startDay));
        min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), min.get(Calendar.DATE), 0, 0, 0);
        max.setTime(sdf.parse(endDay));
        max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), max.get(Calendar.DATE), 23, 59, 59);
        Calendar curr = min;
        while (curr.before(max)) {
            list.add(sdf.format(curr.getTime()));
            curr.add(Calendar.DATE, 1);
        }
        return list;
    }

运行结果截图：
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获取当年所有的月份（yyyy-MM）

/**
     * 获取当年所有月
     *
     * @return
     */

    public static String[] getYearFullMonth() {

        String[] array = new String[12];
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, Integer.parseInt(year.format(new Date())));
        cal.set(Calendar.MONTH, 0);
        for (int i = 0; i < 12; i++) {
            array[i] = sdf.format(cal.getTime());
            cal.add(Calendar.MONTH, 1);
        }
        return array;
    }

两个月份之间的月份（yyyy-MM）

 /**
     * @author bigfaceYang
     *  获取两个日期间年月集合
     * @param minDate 最小时间 2023-01
     * @param maxDate 最大时间 2024-05
     * @return 日期集合 格式为 年-月
     * @throws Exception
     */
    public static List<String> getMonthBetween(String minDate, String maxDate) throws Exception {
        ArrayList<String> result = new ArrayList<String>();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");//格式化为年月

        Calendar min = Calendar.getInstance();
        Calendar max = Calendar.getInstance();

        min.setTime(sdf.parse(minDate));
        min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);

        max.setTime(sdf.parse(maxDate));
        max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);

        Calendar curr = min;
        while (curr.before(max)) {
            result.add(sdf.format(curr.getTime()));
            curr.add(Calendar.MONTH, 1);
        }

        return result;
    }

在这里插入图片描述

根据年份获取年份下所有月份

/**
     * 根据年份获取年份下所有月份
     * @param year
     * @return
     */

    public static String[] getYearFullMonth(String year){


        String[] array = new String[12];
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR,Integer.parseInt(year));
        cal.set(Calendar.MONTH, 0);
        for(int i=0;i<12;i++){
            array[i] = sdf.format(cal.getTime());
            cal.add(Calendar.MONTH, 1);
        }
        return array;
    }

运行结果：

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获取N个月之前的数据

 /**
     * @author wmw
     * 获取当前N个月之前或之后的月份     当num=-1 代表前一个月的数据  num=1 代表后一个月的数据
     * @date 2022/9/14 15:27
     * @return null
     */
    public static String getLastMonth(Integer num){
        SimpleDateFormat month = new SimpleDateFormat("yyyy-MM");
        Calendar c = Calendar.getInstance();
        c.setTime(new Date());
        c.add(Calendar.MONTH,num);
        Date time = c.getTime();
        return month.format(time);
    }
     @SneakyThrows
        public static void main(String[] args) {
            String lastMonth = getLastMonth(2);
            System.out.println(lastMonth);
			//运行结果为：2023-10
        }