java JDK8 时间处理

目录

• 时间格式化
• LocalDate：年月日
• LocalTime：时分秒毫秒
• LocalDateTime：年月日时分秒
• Instant：纳秒时间戳
• Duration:两时间间隔
• Duration：处理两个时间之间的差值
• ZonedDateTime:引入地区

时间格式化

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss");
LocalDateTime localDateTime = LocalDateTime.now();
String localDateTimeStr = formatter.format(localDateTime);
System.out.println(localDateTimeStr);
String str = "2008年08月23日 23:59:59";
DateTimeFormatter formatter2 = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss");
LocalDateTime localDateTime2 = LocalDateTime.parse(str,formatter2);
System.out.println(localDateTime2);

LocalDate：年月日

LocalDate today = LocalDate.now(); // -> 2019-01-31
System.out.println("取当前日期:   "+today);
LocalDate crischristmas = LocalDate.of(2018, 12, 25); // -> 2018-12-25
System.out.println("根据年月日取日期，12月就是12:  "+crischristmas);
LocalDate endOfFeb = LocalDate.parse("2018-12-25"); // 严格按照ISO yyyy-MM-dd验证，02写成2都不行，当然也有一个重载方法允许自己定义格式
System.out.println("根据字符串取： "+endOfFeb);
LocalDate oneToday = today.plus(1, ChronoUnit.WEEKS); // ->2019-02-07
System.out.println("如何获取1周后的日期:  "+oneToday);
LocalDate previousYear = today.minus(1, ChronoUnit.YEARS);
System.out.println("一年前的日期:  "+previousYear);
LocalDate firstDayOfThisMonth = today.with(TemporalAdjusters.firstDayOfMonth()); // 2019-01-01
System.out.println("取本月第1天：  "+firstDayOfThisMonth);
LocalDate secondDayOfThisMonth = today.withDayOfMonth(2); // 2019-01-02
System.out.println("取本月第2天：  "+secondDayOfThisMonth);
LocalDate lastDayOfThisMonth = today.with(TemporalAdjusters.lastDayOfMonth()); // 2019-01-31
System.out.println("取本月最后一天，再也不用计算是28，29，30还是31：  "+lastDayOfThisMonth);
LocalDate firstDay = lastDayOfThisMonth.plusDays(1); // 变成了2019-02-01
System.out.println("取下一天：  "+firstDay);
LocalDate nextSuday = today.with(DayOfWeek.SUNDAY);
System.out.println("下一个周日：  "+nextSuday);
LocalDate nextSaturday = today.with(DayOfWeek.SATURDAY);
System.out.println("下一个周六：  "+nextSaturday);
LocalDate firstMonday = LocalDate.parse("2019-01-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY)); // 2019-01-07
System.out.println("取2019年1月第一个周一  "+firstMonday);
//对比日期是否为同一天（生日对比）
LocalDate birthday = LocalDate.of(1990, 10, 12);
MonthDay birthdayMd = MonthDay.of(birthday.getMonth(), birthday.getDayOfMonth());
MonthDay today = MonthDay.from(LocalDate.of(2019, 10, 12));
System.out.println(today.equals(birthdayMd));

LocalTime：时分秒毫秒

LocalTime now = LocalTime.now(); // 11:09:09.240
System.out.println("时间包含毫秒： "+now);
LocalTime now1 = LocalTime.now().withNano(0); // 11:09:09
System.out.println("时间包含不毫秒"+now1);
LocalTime zero = LocalTime.of(1, 2, 1); // 00:00:00
System.out.println("构造时间:  "+zero);
LocalTime mid = LocalTime.parse("12:00:00"); // 12:00:00
System.out.println("字符串转时间： "+mid);
LocalTime twoHour = LocalTime.now().plusHours(2);
System.out.println("添加2小时： "+twoHour);

LocalDateTime：年月日时分秒

LocalDateTime ldt1 = LocalDateTime.of(2017, Month.JANUARY, 4, 17, 23, 52);
System.out.println("创建日期时间方法一： "+ldt1);
LocalDate localDate = LocalDate.of(2017, Month.JANUARY, 4);
LocalTime localTime = LocalTime.of(17, 23, 52);
LocalDateTime ldt2 = localDate.atTime(localTime);
System.out.println("创建日期时间方法二： "+ldt2);

Instant：纳秒时间戳

LocalDate date = ldt1.toLocalDate();
System.out.println("日期时间获取日期"+date);
LocalTime time = ldt1.toLocalTime();
System.out.println("日期时间获取时间"+time);
Instant instantNow =Instant.now();
System.out.println("时间戳（精确到纳秒）nanos表示纳秒部分 ： "+instantNow.toEpochMilli()+instantNow.getNano());
Instant instant = Instant.ofEpochSecond(120, 100000);
System.out.println("时间戳（精确到纳秒） ： "+instant);

Duration:两时间间隔

LocalDateTime from = LocalDateTime.of(2019, Month.JANUARY, 5, 10, 7, 0);    // 2019-01-05 10:07:00
LocalDateTime to = LocalDateTime.of(2019, Month.FEBRUARY, 5, 10, 7, 0);     // 2019-02-05 10:07:00
Duration duration = Duration.between(from, to);     // 表示从 2019-01-05 10:07:00 到 2019-02-05 10:07:00 这段时间
long days = duration.toDays();
System.out.println("这段时间的总天数"+days);
long hours = duration.toHours();
System.out.println("这段时间的小时数"+hours);
long minutes = duration.toMinutes();
System.out.println("这段时间的分钟数"+minutes);
long seconds = duration.getSeconds();
System.out.println("这段时间的秒数"+seconds);
long milliSeconds = duration.toMillis();
System.out.println("这段时间的毫秒数"+milliSeconds);
long nanoSeconds = duration.toNanos();
System.out.println("这段时间的纳秒数"+nanoSeconds);

Duration：处理两个时间之间的差值

Duration duration1 = Duration.of(5, ChronoUnit.DAYS);       // 5天
System.out.println("这段时间的分钟数"+duration1.toMinutes());
Duration duration2 = Duration.of(1000, ChronoUnit.MILLIS);  // 1000毫秒
System.out.println("这段时间的分钟数"+duration2.toMinutes());

ZonedDateTime:引入地区

ZonedDateTime zonedDateTime = ZonedDateTime.now();
System.out.println(zonedDateTime);
Instant instant = Instant.now();
ZoneId zoneId1 = ZoneId.of("GMT");
ZonedDateTime zonedDateTime2 = ZonedDateTime.ofInstant(instant,zoneId1);
System.out.println(zonedDateTime2);