Java常用日期工具实现

系统管理员 2023-01-10 05:26 30阅读 0赞

1.  获取今日日期
2.  获取本月第一天日期
3.  获取本月最后一天日期
4.  date转日期字符串
5.  日期字符串转date
6.  日期字符串格式化
7.  根据date获取past天前的日期
8.  获取当前年周数:yyyy-w
9.  获取范围时间内的日期集合

public class MyDateUtils {
        public static final String NORMAL_DATE_FORMAT = "yyyy-MM-dd";
        public static final String NORMAL_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm";
    
        /**
         * 获取今日日期 yyyy-MM-dd
         */
        public static String getToday() {
            return LocalDate.now().toString();
        }
    
        /**
         * 获取本月第一天日期 2019-11-01
         */
        public static String getFirstDayOfMonth() {
            return LocalDate.now().with(TemporalAdjusters.firstDayOfMonth()).toString();
        }
    
        /**
         * 获取本月最后一天日期 2019-11-30
         */
        public static String getLastDayOfMonth() {
            return LocalDate.now().with(TemporalAdjusters.lastDayOfMonth()).toString();
        }
    
        /**
         * date转字符串
         */
        public static String dateToDateStr(Date date, String format) {
            DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
            Instant instant = date.toInstant();
            ZoneId zoneId = ZoneId.systemDefault();
            LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zoneId);
            return dateTimeFormatter.format(localDateTime);
        }
    
        public static String dateToDateStr(Date date) {
            return dateToDateStr(date, NORMAL_DATE_FORMAT);
        }
    
        /**
         * 日期字符串转date
         */
        public static Date dateStrToDate(String dateStr, String format) {
            DateTimeFormatter dateDtf = DateTimeFormatter.ofPattern(format);
            LocalDate localDate = LocalDate.parse(dateStr, dateDtf);
            ZoneId zone = ZoneId.systemDefault();
            Instant instant = localDate.atStartOfDay(zone).toInstant();
            return Date.from(instant);
        }
    
        public static Date dateStrToDate(String dateStr) {
            return dateStrToDate(dateStr, NORMAL_DATE_FORMAT);
        }
    
        /**
         * 日期字符串格式化
         */
        public static String dateStrFormat(String dateStr, String formatTo) {
            DateTimeFormatter dateDtf1 = DateTimeFormatter.ofPattern(NORMAL_DATE_FORMAT);
            LocalDate localDate = LocalDate.parse(dateStr, dateDtf1);
            DateTimeFormatter dateDtf2 = DateTimeFormatter.ofPattern(formatTo);
            return dateDtf2.format(localDate);
        }
    
        /**
         * 根据date获取past天前的日期
         */
        public static Date getPastDate(Date date, int past) {
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past);
            return calendar.getTime();
        }
    
        public static String getPastDate(String dateStr, int past) {
            Date date = dateStrToDate(dateStr);
            return dateToDateStr(getPastDate(date, past));
        }
    
        public static String getYesterday(String dateStr) {
            return getPastDate(dateStr, 1);
        }
        
        /**
         * 当前年周数:yyyy-w
         */
        public static String getYearWeek(Date date) {
            Calendar cal = Calendar.getInstance();
            cal.setTime(date);
            //设置一周的第一天是周一
            cal.setFirstDayOfWeek(Calendar.MONDAY);
    
            int year = cal.get(Calendar.YEAR);
            int week = cal.get(Calendar.WEEK_OF_YEAR);
    
            cal.add(Calendar.DAY_OF_MONTH, -7);  //上一周
    
            //判断是否同一年，并且本周周数小于上周周数，则在上周周数的基础上加一
            if (year == cal.get(Calendar.YEAR) && week < cal.get(Calendar.WEEK_OF_YEAR)) {
                week = cal.get(Calendar.WEEK_OF_YEAR) + 1;
            }
            
            return year + "-" + week;
        }
    
        /**
         * 获取范围时间内的日期集合
         */
        public static List<String> getBetweenDays(String startDate, String endDate) {
            if (StringUtils.isBlank(startDate) || StringUtils.isBlank(endDate)) {
                return Collections.emptyList();
            }
    
            Date start = dateStrToDate(startDate);
            Date end = dateStrToDate(endDate);
    
            if (start.compareTo(end) > 0) {
                return Collections.emptyList();
            }
    
            // 返回的日期集合
            List<String> days = new ArrayList<>();
            Calendar tempStart = Calendar.getInstance();
            tempStart.setTime(start);
    
            Calendar tempEnd = Calendar.getInstance();
            tempEnd.setTime(end);
            tempEnd.add(Calendar.DATE, 1);
            while (tempStart.before(tempEnd)) {
                days.add(dateToDateStr(tempStart.getTime()));
                tempStart.add(Calendar.DAY_OF_YEAR, 1);
            }
    
            return days;
        }
    
    }