jdk1.8新增的三个日期类

  • LocalDate
  • LocalTime
  • LocalDateTime

以及格式化类(线程安全)

private static DateTimeFormatter dateFormatter = DateTiemFormatter.ofPattern(“yyyy-M-d”);

  1. package basics;
  3. import java.time.*;
  4. import java.time.format.DateTimeFormatter;
  5. import java.time.temporal.ChronoUnit;
  6. import java.time.temporal.TemporalAdjusters;
  7. import java.util.Date;
  9. /**
  10.  * @author Created by yinrg on 2022年3月25日, 0025 下午 5:04
  11.  * @fileSimpleName DateDemo2
  12.  * @fileName basics.DateDemo2
  13.  * @description JDK1.8新增的时间API
  14.  */
  15. public class DateDemo2 {
  16.     private static DateTimeFormatter dateTimeFormatter01 = DateTimeFormatter.ofPattern("yyyy-M-d");
  17.     private static DateTimeFormatter dateTimeFormatter02 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
  18.     private static DateTimeFormatter dateTimeFormatter03 = DateTimeFormatter.ofPattern("yyyy-M-d H:m:s");
  20.     public static void main(String[] args) {
  22.         /**
  23.          * parse() 使用特定格式化程序从文本字符串中获取LocalDate的实例。
  24.          * 使用格式化程序解析文本，返回日期。
  25.          */
  26.         LocalDate ld01 = LocalDate.parse("2022-03-01");
  27.         LocalDate ld02 = LocalDate.parse("2022-03-9", dateTimeFormatter01);
  28.         LocalDate ld03 = LocalDate.parse("2022-03-01", dateTimeFormatter02);
  29.         System.out.println(ld01);
  30.         System.out.println(ld02);
  31.         System.out.println(ld03);
  33.         // 格式化操作
  34.         System.out.println(dateTimeFormatter01.format(ld01));
  35.         System.out.println(dateTimeFormatter01.format(ld02));
  36.         System.out.println(dateTimeFormatter02.format(ld03));
  38.         System.out.println(daysBetween(ld01, ld02));
  39.         System.out.println(weekSunday(ld01));
  40.         System.out.println(weekMonday(ld02));
  41.         System.out.println(monthEnd(ld02));
  42.         System.out.println(monthStart(ld02));
  44.         // LocalDateTime
  45.         System.out.println(LocalDateTime.parse("2022-3-21 11:11:11", dateTimeFormatter03)); // 2022-03-21T11:11:11
  46.         /**
  47.          * LocalDateTime与Date之间的互相转换
  48.          * new Date().getTime() 是Date转Long
  49.          * new Date(long time) 是long转Date
  50.          */
  51.         long nowMillisecond = getMillisecond(LocalDateTime.now());
  52.         System.out.println(new Date(nowMillisecond));
  53.     }
  55.     /**
  56.      *  LocalDateTime转Long
  57.      * @param dateTime
  58.      * @return
  59.      */
  60.     public static long getMillisecond(LocalDateTime dateTime){
  61.         return dateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
  62.     }
  64.     /**
  65.      * Long转LocalDateTime
  66.      * @param timestamp
  67.      * @return
  68.      */
  69.     public static LocalDateTime parse(Long timestamp){
  70.         Instant instant = Instant.ofEpochMilli(timestamp);
  71.         ZoneId zone = ZoneId.systemDefault();
  72.         return LocalDateTime.ofInstant(instant,zone);
  73.     }
  76.     /**
  77.      * 获取两个日期之间差值
  78.      *
  79.      * @param from
  80.      * @param to
  81.      * @return
  82.      */
  83.     public static long daysBetween(LocalDate from, LocalDate to) {
  84.         return from.until(to, ChronoUnit.DAYS);
  85.     }
  87.     /**
  88.      * 获取所在周日是哪一天
  89.      *
  90.      * @param date
  91.      * @return
  92.      */
  93.     public static LocalDate weekSunday(LocalDate date) {
  94.         return date.plusDays(7 - date.getDayOfWeek().getValue());
  95.     }
  97.     /**
  98.      * 获取所在周一是哪一天
  99.      *
  100.      * @param date
  101.      * @return
  102.      */
  103.     public static LocalDate weekMonday(LocalDate date) {
  104.         DayOfWeek dayOfWeek = date.getDayOfWeek();
  105.         return date.minusDays(dayOfWeek.getValue() - 1);
  106.     }
  108.     /**
  109.      * 获取所在月末是哪一天
  110.      *
  111.      * @param date
  112.      * @return
  113.      */
  114.     public static LocalDate monthEnd(LocalDate date) {
  115.         return date.with(TemporalAdjusters.lastDayOfMonth());
  116.     }
  118.     /**
  119.      * 获取所在月初是哪一天
  120.      *
  121.      * @param date
  122.      * @return
  123.      */
  124.     public static LocalDate monthStart(LocalDate date) {
  125.         return LocalDate.of(date.getYear(), date.getMonth(), 1);
  126.     }
  129. }