Java8-java.time-常用API

基于之前博客文章中列举了time的一些基本API，本文主要列举实际开发中需要经常用到的。
  1 package com.gzh.time;
  2 
  3 import java.time.DayOfWeek;
  4 import java.time.Instant;
  5 import java.time.LocalDate;
  6 import java.time.LocalDateTime;
  7 import java.time.LocalTime;
  8 import java.time.Period;
  9 import java.time.ZoneId;
 10 import java.time.format.DateTimeFormatter;
 11 import java.time.temporal.TemporalAdjusters;
 12 import java.util.Calendar;
 13 import java.util.Date;
 14 
 15 import org.junit.Test;
 16 
 17 public class TimeTest {
 18     
 19     // LocalDate;LocalTime;LocalDateTime
 20     @Test
 21     public void test() {
 22         
 23         // 获取当前时间:2020-03-08
 24         System.out.println(LocalDate.now());
 25         // 获取当前时间:15:20:40.158
 26         System.out.println(LocalTime.now());
 27         // 获取当前时间:2020-03-08T15:20:40.158
 28         System.out.println(LocalDateTime.now());
 29         
 30         // DateTimeFormatter---ISO系类转化
 31         // BASIC_ISO_DATE :20200308
 32         System.out.println("BASIC_ISO_DATE :" + DateTimeFormatter.BASIC_ISO_DATE.format(LocalDateTime.now()));
 33         // ISO_DATE :2020-03-08
 34         System.out.println("ISO_DATE :" + DateTimeFormatter.ISO_DATE.format(LocalDateTime.now()));
 35         // ISO_DATE_TIME :2020-03-08T16:33:27.489
 36         System.out.println("ISO_DATE_TIME :" + DateTimeFormatter.ISO_DATE_TIME.format(LocalDateTime.now()));
 37         // ISO_LOCAL_DATE :2020-03-08
 38         System.out.println("ISO_LOCAL_DATE :" + DateTimeFormatter.ISO_LOCAL_DATE.format(LocalDateTime.now()));
 39         // ISO_LOCAL_DATE_TIME :2020-03-08T16:33:27.49
 40         System.out.println("ISO_LOCAL_DATE_TIME :" + DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(LocalDateTime.now()));
 41         // ISO_LOCAL_TIME :16:33:27.49
 42         System.out.println("ISO_LOCAL_TIME :" + DateTimeFormatter.ISO_LOCAL_TIME.format(LocalDateTime.now()));
 43         // ISO_ORDINAL_DATE :2020-068
 44         System.out.println("ISO_ORDINAL_DATE :" + DateTimeFormatter.ISO_ORDINAL_DATE.format(LocalDateTime.now()));
 45         // ISO_TIME :16:33:27.49
 46         System.out.println("ISO_TIME :" + DateTimeFormatter.ISO_TIME.format(LocalDateTime.now()));
 47         // ISO_WEEK_DATE :2020-W10-7
 48         System.out.println("ISO_WEEK_DATE :" + DateTimeFormatter.ISO_WEEK_DATE.format(LocalDateTime.now()));
 49         
 50         // DateTimeFormatter格式转化
 51         DateTimeFormatter dtf1 = DateTimeFormatter.ofPattern("yyyy-MM-dd"); // ISO_DATE;ISO_LOCAL_DATE
 52         DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("HH:mm:ss");
 53         DateTimeFormatter dtf3 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
 54         // 转化日期:2020-03-08
 55         System.out.println(dtf1.format(LocalDate.now()));
 56         // 转化日期:2020-03-08
 57         System.out.println(dtf1.format(LocalDateTime.now()));
 58         // 转化日期:15:20:40
 59         System.out.println(dtf2.format(LocalTime.now()));
 60         // 转化日期:15:20:40
 61         System.out.println(dtf2.format(LocalDateTime.now()));
 62         // 转化日期:2020-03-08 15:20:40
 63         System.out.println(dtf3.format(LocalDateTime.now()));
 64         
 65         LocalDateTime ldt1 = LocalDateTime.of(2020, 12, 12, 0, 0, 0);
 66         // LocalDateTime-->LocalDate
 67         LocalDate localDate1 = ldt1.toLocalDate();
 68         // LocalDateTime-->LocalTime
 69         LocalTime localTime1 = ldt1.toLocalTime();
 70         
 71         // java.util.Date --> LocalDateTime
 72         LocalDateTime ldt2 = LocalDateTime.ofInstant(new Date().toInstant(), ZoneId.systemDefault());
 73         // LocalDateTime -->java.util.Date
 74         LocalDate localDate2 = LocalDate.now();
 75         LocalTime localTime2 = LocalTime.now();
 76         LocalDateTime localDateTime2 = LocalDateTime.of(localDate2, localTime2);
 77         Instant instant = localDateTime2.atZone(ZoneId.systemDefault()).toInstant();
 78         System.out.println(Date.from(instant));
 79         
 80         // LocalDate常用
 81         // 计算时间差--天数差
 82         LocalDate localDate3 = LocalDate.of(2008, 1, 1);
 83         LocalDate localDate4 = LocalDate.of(2018, 12, 12);
 84         // 天数差:3998
 85         System.out.println("天数差 :" + (localDate4.toEpochDay()-localDate3.toEpochDay()));
 86         
 87         // 计算当年是否是闰年:isLeapYear()
 88         System.out.println("isLeapYear :" + LocalDate.now().isLeapYear());
 89         
 90         // 计算生日
 91         Period betweenDate = Period.between(LocalDate.now(), LocalDate.of(2000, 12, 31));
 92         int age = betweenDate.getYears();
 93         System.out.println(age);
 94         
 95         // 利用时间矫正器TemporalAdjuster
 96         LocalDate localDate5 = LocalDate.now();
 97         // LocalDate.with(TemporalAdjuster adjuster):利用TemporalAdjuster的工具类TemporalAdjusters
 98         LocalDate firstDayOfMonth = localDate5.with(TemporalAdjusters.firstDayOfMonth());
 99         System.out.println("firstDayOfMonth :"+ firstDayOfMonth);
100         TemporalAdjusters.firstDayOfYear();
101         TemporalAdjusters.lastDayOfMonth();
102         TemporalAdjusters.lastDayOfYear();
103         TemporalAdjusters.firstDayOfNextMonth();
104         TemporalAdjusters.firstDayOfNextYear();
105         // 计算某一天的下一个工作日 :@FunctionalInterface--TemporalAdjuster
106         LocalDate nextWorkDay = localDate5.with((time)->{
107             LocalDate localDate =(LocalDate) time;
108             if(localDate.getDayOfWeek().equals(DayOfWeek.FRIDAY)) {
109                 return localDate.plusDays(3);
110             }else if(localDate.getDayOfWeek().equals(DayOfWeek.SATURDAY)){
111                 return localDate.plusDays(2);
112             }else {
113                 return localDate.plusDays(1);
114             }
115  
116         });
117         System.out.println("nextWorkDay" + nextWorkDay);
118     }
119     
120 }