详解Java中日期工具类的操作

           cn.hutoolhutool-all${hutool.version}

    //字符串转Date Date dateTime = DateUtil.parseDate("2022-04-06"); System.out.println(dateTime); 

//Date转字符串不指定format格式，默认yyyy-MM-dd HH:mm:ss String dateStr = DateUtil.date2Str(new Date()); System.out.println(dateStr); //Date转字符串指定格式 String dateStr2 = DateUtil.date2Str("yyyy/MM/dd",new Date()); System.out.println(dateStr2); 

//字符串转LocalDate LocalDate localDate = DateUtil.parseLocalDate("2022-04-06"); System.out.println(localDate); 

//Date转LocalDate LocalDate localDate = DateUtil.date2LocalDate(new Date()); System.out.println(localDate); 

//LocalDate转Str String localDateStr = DateUtil.localDate2Str(LocalDate.now()); System.out.println(localDateStr); 

String beginDateStr = "2022-02-01 22:33:23"; Date beginDate = DateUtil.parse(beginDateStr); String endDateStr = "2022-03-10 23:33:23"; Date endDate = DateUtil.parse(endDateStr); //相差天数(37) long betweenDay = DateUtil.between(beginDate, endDate, DateUnit.DAY); System.out.println(betweenDay); //格式化时间差(37天1小时) String formatBetween = DateUtil.formatBetween(beginDate, endDate, BetweenFormater.Level.HOUR); System.out.println(formatBetween); 

String dateStr = "2022-04-07 10:33:23"; Date date = DateUtil.parse(dateStr); //一天的开始时间：2022-04-07 00:00:00 Date beginOfDay = DateUtil.beginOfDay(date); System.out.println(beginOfDay); //一天的结束时间：2022-04-07 23:59:59 Date endOfDay = DateUtil.endOfDay(date); System.out.println(endOfDay); 

/** * 
基于hutool的日期工具类增强
 * * @author zjq * @date 2021/04/07 */ public class DateUtil extends cn.hutool.core.date.DateUtil { private static final String[] PARSE_PATTERNS = { "yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd HH:mm", "yyyy-MM", "yyyy/MM/dd", "yyyy/MM/dd HH:mm:ss", "yyyy/MM/dd HH:mm", "yyyy/MM", "yyyy.MM.dd", "yyyy.MM.dd HH:mm:ss", "yyyy.MM.dd HH:mm", "yyyy.MM"}; public static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("HH:mm:ss"); public static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd"); public static final DateTimeFormatter DATETIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); /** * 字符串转date类型 * * @param dateStr * @return */ public static Date parseDate(Object dateStr) { if (ObjectUtils.isNull(dateStr)) { return null; } if (dateStr instanceof Double) { return org.apache.poi.ss.usermodel.DateUtil.getJavaDate((Double) dateStr); } return parse(dateStr.toString(), PARSE_PATTERNS); } /** * Date类型转字符串 * * @param date * @return yyyy-MM-dd HH:mm:ss */ public static String date2Str(Date date) { return date2Str(null, date); } /** * Date类型转字符串 * * @param format * @param date * @return */ public static String date2Str(String format, Date date) { if (ObjectUtils.isNull(date)) { return null; } SimpleDateFormat dateFormat = StrUtil.isNotBlank(format) ?new SimpleDateFormat(format): new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); return dateFormat.format(date); } /** * 字符串转LocalTime类型 * * @param dateStr * @return */ public static LocalTime parseLocalTime(Object dateStr) { if (ObjectUtils.isNull(dateStr)) { return null; } if (dateStr instanceof Double) { return date2LocalTime(parseDate(dateStr)); } return LocalTime.parse(dateStr.toString(), TIME_FORMATTER); } /** * Date转LocalTime * * @param date * @return */ public static LocalTime date2LocalTime(Date date) { if (null == date) { return null; } return date.toInstant().atZone(ZoneId.systemDefault()).toLocalTime(); } /** * LocalTime转Str * * @param localTime * @return HH:mm:ss */ public static String localTime2Str(LocalTime localTime) { return localTime2Str(null, localTime); } /** * LocalTime转str * * @param format    格式 * @param localTime * @return */ public static String localTime2Str(String format, LocalTime localTime) { if (null == localTime) { return null; } DateTimeFormatter formatter = StrUtil.isBlank(format) ? TIME_FORMATTER : DateTimeFormatter.ofPattern(format); return localTime.format(formatter); } /** * 字符串转LocalDate类型 * * @param dateStr * @return */ public static LocalDate parseLocalDate(Object dateStr) { if (ObjectUtils.isNull(dateStr)) { return null; } if (dateStr instanceof Double) { return date2LocalDate(parseDate(dateStr)); } return LocalDate.parse(dateStr.toString(), DATE_FORMATTER); } /** * Date转LocalDate * * @param date * @return */ public static LocalDate date2LocalDate(Date date) { if (null == date) { return null; } return date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate(); } /** * LocalDate转Str * * @param localDate * @return */ public static String localDate2Str(LocalDate localDate) { return localDate2Str(null, localDate); } /** * LocalDate转Str * * @param format    格式 * @param localDate * @return */ public static String localDate2Str(String format, LocalDate localDate) { if (null == localDate) { return null; } DateTimeFormatter formatter = StrUtil.isBlank(format) ? DATE_FORMATTER : DateTimeFormatter.ofPattern(format); return localDate.format(formatter); } /** * 字符串转LocalDateTime类型 * * @param dateStr * @return */ public static LocalDateTime parseLocalDateTime(Object dateStr) { if (ObjectUtils.isNull(dateStr)) { return null; } if (dateStr instanceof Double) { return date2LocalDateTime(parseDate(dateStr)); } return LocalDateTime.parse(dateStr.toString(), DATETIME_FORMATTER); } /** * Date转LocalDateTime * * @param date * @return */ public static LocalDateTime date2LocalDateTime(Date date) { if (null == date) { return null; } return date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime(); } /** * LocalDate转Str * * @param localDateTime * @return */ public static String localDateTime2Str(LocalDateTime localDateTime) { return localDateTime2Str(null, localDateTime); } /** * LocalDate转Str * * @param format * @param localDateTime * @return */ public static String localDateTime2Str(String format, LocalDateTime localDateTime) { if (null == localDateTime) { return null; } DateTimeFormatter formatter = StrUtil.isBlank(format) ? DATETIME_FORMATTER : DateTimeFormatter.ofPattern(format); return localDateTime.format(formatter); } }