学习Java8中的日期类
2022-03-15 本文已影响0人
青年心路
public class Main {
public static void main(String[] args) {
// 获取今日日期
// getToday();
// 获取详细的年月日
// getYearAndMonthAndDay();
// 自定义日期
// customDate();
// 判断日期是否相等
// checkIsEqualsTo();
// 检查周期性日期
// checkCycleDate();
// 计算下一周后的日期
// getNextWeekDate();
// 获取前一年和后一年的日期
// getBeforeAndNextYear();
// 判断日期在当前之前还是之后
// checkCurDateIsBeforeOrAfter();
// 检查是否是闰年
// checkLeapYear();
// 获取当前时间（不含年月日）
// getCurTime();
// 时间加减计算
// timePlusAndMinus();
// 通过Clock时钟获取时间
// useClock();
// 在特定时区下的当前时间
// useZoneDateTime();
// 获取当前年月
// getYearAndMonth();
// 获取当月的天数
// getDayCountInCurMonth();
// 获取当前时间和指定时间的时间间隔
// getTimeGap();
// 通过Duration计算当前日期与指定日期的时间差
// getTimeGapUseDuration();
// 获取当前的时间戳
// getTimestamp();
// 解析指定时间
// parseDate();
// 字符串转时间
// stringToDate();
// Date与Instant互转
// dateToInstant();
// Date转LocalDateTime
// dateToLocalDateTime();
// 毫秒转LocalDateTime
// msToLocalDateTime();
// LocalDateTime转MS
// localDateTimeToMS();
// LocalDate转Date
localDateTimeToDate();
}
/******************************年月日*********************************/
/**
* 获取今日日期
*/
public static void getToday() {
LocalDate today = LocalDate.now();
System.out.println(today);
}
/**
* 获取详细的年月日
*/
public static void getYearAndMonthAndDay() {
LocalDate today = LocalDate.now();
System.out.println(today.getYear());
System.out.println(today.getMonth().getValue());
System.out.println(today.getDayOfMonth());
System.out.println(today.getDayOfWeek().getValue());
System.out.println(today.getDayOfYear());
}
/**
* 自定义日期
*/
public static void customDate() {
LocalDate date = LocalDate.of(2020, 5, 21);
System.out.println(date);
}
/**
* 判断日期是否相等
*/
public static void checkIsEqualsTo() {
LocalDate date1 = LocalDate.now();
LocalDate date2 = LocalDate.of(2022, 3, 15);
System.out.println(date1.equals(date2));
}
/**
* 检查周期性事件（如：生日）
*/
public static void checkCycleDate() {
LocalDate date1 = LocalDate.now();
LocalDate date2 = LocalDate.of(2020, 3, 15);
MonthDay birthday = MonthDay.of(date2.getMonth(), date2.getDayOfMonth());
MonthDay curDay = MonthDay.from(date1);
if (curDay.equals(birthday)) {
System.out.println("生日快乐");
} else {
System.out.println("又是平凡的一天");
}
}
/**
* 计算一周后的日期
*/
public static void getNextWeekDate() {
LocalDate today = LocalDate.now();
System.out.println("今天的日期：" + today);
LocalDate nextWeekDate = today.plus(1, ChronoUnit.WEEKS);
System.out.println("一周后的日期：" + nextWeekDate);
}
/**
* 计算前一年和下一年的日期
*/
public static void getBeforeAndNextYear() {
LocalDate today = LocalDate.now();
LocalDate beforeYear = today.minus(1, ChronoUnit.YEARS);
System.out.println(beforeYear);
LocalDate nextYear = today.plus(1, ChronoUnit.YEARS);
System.out.println(nextYear);
}
/**
* 判断当前日期相对于另一个日期是早还是晚
*/
public static void checkCurDateIsBeforeOrAfter() {
LocalDate today = LocalDate.now();
LocalDate tomorrow = today.plusDays(1);
if (tomorrow.isAfter(today)) {
System.out.println("之后的日期: " + tomorrow);
}
LocalDate yesterday = today.minusDays(1);
if (yesterday.isBefore(today)) {
System.out.println("之前的日期：" + yesterday);
}
}
public static void checkLeapYear() {
LocalDate today = LocalDate.now();
if (today.isLeapYear()) {
System.out.println("当前是闰年");
} else {
System.out.println("当前是平年");
}
}
/******************************时分秒*********************************/
/**
* 获取当前时间（不含年月日）
*/
public static void getCurTime() {
LocalTime time = LocalTime.now();
System.out.println(time);
}
/**
* 时间加减计算
*/
public static void timePlusAndMinus() {
LocalTime now = LocalTime.now();
System.out.println("三小时后：" + now.plusHours(3));
System.out.println("三小时前：" + now.minusHours(3));
}
/**
* Clock时钟的使用，用于获取不同时区下的时间
*/
public static void useClock() {
Clock clock = Clock.systemUTC();
System.out.println("clock: " + clock.instant());
Clock defaultClock = Clock.systemDefaultZone();
System.out.println("default clock: " + defaultClock.instant());
}
/**
* 通过ZoneDateTime表示某时区下的时间
*/
public static void useZoneDateTime() {
ZoneId newYork = ZoneId.of("America/New_York");
LocalDateTime localDateTime = LocalDateTime.now();
ZonedDateTime dateAndTimeInNewYork = ZonedDateTime.of(localDateTime, newYork);
System.out.println("在特定地区的当前日期和时间：" + dateAndTimeInNewYork);
}
/******************************年月*********************************/
/**
* 获取当前年月
*/
public static void getYearAndMonth() {
YearMonth curYearAndMonth = YearMonth.now();
System.out.println(curYearAndMonth);
}
/**
* 获取当月天数
*/
public static void getDayCountInCurMonth() {
YearMonth yearMonth = YearMonth.now();
System.out.println(yearMonth.lengthOfMonth());
}
/**
* 通过Period计算当前时间和某个时间的间隔
*
* getMonths()和getDays()的值
* 5.10/5.1: 1,9
* 5.10/4.1:1,9 (月份和天数相加才是真正相差的数)
* 6.10/4.1:2,9 (月份和天数相加才是真正相差的数)
*/
public static void getTimeGap() {
LocalDate today = LocalDate.now();
LocalDate startLearn = LocalDate.of(2022, 2, 7);
Period period = Period.between(today, startLearn);
System.out.println("时间间隔：" + period.getMonths());
}
/**
* 通过Duration计算时间差值
*/
public static void getTimeGapUseDuration() {
LocalDateTime today = LocalDateTime.now();
LocalDateTime beforeWeek = today.minusWeeks(1);
Duration duration = Duration.between(today, beforeWeek);
System.out.println(duration.toHours());
}
/******************************Instant时间戳*********************************/
/**
* 获取当前时间的时间戳
*/
public static void getTimestamp() {
long timestamp1 = LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
System.out.println(timestamp1);
long timestamp2 = Instant.now().toEpochMilli();
System.out.println(timestamp2 + " " + new Date().getTime());
}
/******************************使用指定的格式解析时间*********************************/
/**
* 通过指定的格式解析时间
*/
public static void parseDate() {
String curDate = "20220315";
LocalDate localDate = LocalDate.parse(curDate, DateTimeFormatter.BASIC_ISO_DATE);
System.out.println(localDate);
}
/**
* 字符串互转日期类型
*/
public static void stringToDate() {
LocalDateTime date = LocalDateTime.now();
DateTimeFormatter formatter1 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String str = date.format(formatter1);
System.out.println("日期转换为字符串：" + str);
DateTimeFormatter format2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime date2 = LocalDateTime.parse(str, format2);
System.out.println("日期类型：" + date2);
}
/**
* Date和Instant互转
*/
public static void dateToInstant() {
// Instant转Date
Date date = Date.from(Instant.now());
// Date转Instant
Instant instant = date.toInstant();
System.out.println(date);
System.out.println(instant);
}
/**
* Date转LocalDateTime
*/
public static void dateToLocalDateTime() {
LocalDateTime localDateTime = new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
System.out.println(localDateTime);
}
/**
* 毫秒转LocalDateTime
*/
public static void msToLocalDateTime() {
LocalDateTime localDateTime = LocalDateTime.ofInstant(
Instant.ofEpochMilli(new Date().getTime()), ZoneId.systemDefault()
);
System.out.println(localDateTime);
}
/**
* LocalDateTime转毫秒
*/
public static void localDateTimeToMS() {
long milli = LocalDateTime.of(2020, 3, 1, 0, 0, 0)
.toInstant(ZoneOffset.of("+8")).toEpochMilli();
System.out.println(milli);
}
/**
* LocalDate转Date
*/
public static void localDateTimeToDate() {
LocalDate now = LocalDate.now();
Date date = Date.from(now.atStartOfDay(ZoneId.systemDefault()).toInstant());
System.out.println(date);
}
}
