01. 获取当前日期
格式：yyyy-MM-dd
LocalDate today = LocalDate.now();
System.out.println("今天的日期：" + today);
02. 获取日期中的年/月/日
getMonthValue() 获取月
getDayOfMonth() 获取天
LocalDate today = LocalDate.now();
int year = today.getYear();
System.out.println("年：" + year);
03. 创建自定义日期
LocalDate date = LocalDate.of(2060, 02, 17);
System.out.println("自定义时间：" + date);
04. 判断两个日期是否相等
LocalDate today = LocalDate.now();
LocalDate demoDate = LocalDate.of(2020, 2, 25);
if (today.equals(demoDate)) {
System.out.println("两个时间相等！");
} else {
System.out.println("两个时间不相等！");
}
05. 判断日期周期性 例如：国庆节
LocalDate national = LocalDate.of(2020, 10, 1);
MonthDay monthDay = MonthDay.of(national.getMonth(), national.getDayOfMonth());
MonthDay currentMonthDay = MonthDay.from(today);
if(currentMonthDay.equals(monthDay)){
System.out.println("国庆节到啦，举国同庆！");
}else{
System.out.println("国庆节还没到！");
}
06. 获取当前时间
LocalTime time = LocalTime.now();
System.out.println("当前时间：" + time);
07. 获取指定N小时/N分/N秒后的时间
plusMinutes(9) 9分钟后
plusSeconds(9) 9秒钟后
LocalTime time = LocalTime.now();
LocalTime plusHours = time.plusHours(9);
System.out.println("9小时后：" + plusHours);
08. 计算N天/N周/N月/N年后的日期 ChronoUnit声明单位
LocalDate today = LocalDate.now();
LocalDate plusYears = today.plus(2, ChronoUnit.YEARS);
System.out.println("两年后：" + plusYears);
09. 计算N天/N周/N月/N年前的日期 ChronoUnit声明单位
LocalDate today = LocalDate.now();
LocalDate minusYears = today.minus(2, ChronoUnit.YEARS);
System.out.println("两年前：" + minusYears);
10. Clock时钟类，获取当前时间戳
Clock clock = Clock.systemUTC();
System.out.println("当前时间戳：" + clock.millis());
Clock systemDefaultClock = Clock.systemDefaultZone();
System.out.println("当前默认时区时间戳：" + systemDefaultClock.millis());
11. 判断某个日期小于或大于指定日期 isAfter/isBefore
LocalDate today = LocalDate.now();
if(today.isAfter(future)){
System.out.println("在指定日期之前");
}else{
System.out.println("在指定日期之后");
}
12. 时区处理
ZoneId americaZone = ZoneId.of("America/New_York");
LocalDateTime localDateTime = LocalDateTime.now();
ZonedDateTime americaZoneTime = ZonedDateTime.of(localDateTime, americaZone);
System.out.println("当前时间的美国纽约时间：" + americaZoneTime);
13. 获取当前年月/当前月份多少天
YearMonth currentYearMonth = YearMonth.now();
System.out.println("当前年月：" + currentYearMonth);
System.out.println("当前月份有多少天：" + currentYearMonth.lengthOfMonth());
YearMonth futureYearMonth = YearMonth.of(2021, Month.FEBRUARY);
System.out.println("指定年月：" + futureYearMonth);
14. 校验日期是否是闰年
isLeapYear()函数，闰年返回true，否则返回false
if(today.isLeapYear()){
System.out.println(today.getYear() + "是闰年！");
}else {
System.out.println(today.getYear() + "不是闰年！");
}
15. 计算两个时间之间的天数/月数
LocalDate today = LocalDate.now();
LocalDate futureLocalDate = LocalDate.of(2020, 3, 25);
Period period = Period.between(today, futureLocalDate);
System.out.println("两个日期相差：" + period.getMonths() + "月！");
16. 获取当前时间戳
Instant instant = Instant.now();
System.out.println("当前时间戳：" + instant.toEpochMilli());
17. 格式化日期
String strDate = "20220101";
LocalDate parseLocalDate = LocalDate.parse(strDate, DateTimeFormatter.BASIC_ISO_DATE);
System.out.println("格式化后的日期：" + parseLocalDate);
18. 字符串日期互转
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
String strNow = now.format(format);
System.out.println("日期转字符串：" + strNow);
System.out.println("字符串转日期：" + LocalDate.parse(strNow, format));
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