操作包括

java.util.Date().getTime()返回13位时间戳

System.currentTimeMillis 计算毫秒差

SimpleDateFormat 解析和格式化日期

LocalDate

LocalTime

LocalDateTime

Duration

Period

计算日间隔 toEpochDay

日期相互加减

日期时间和日期相互转换

时间类型和时间戳互相转化

java.util.Date().getTime()

返回13位时间戳

long a = new java.util.Date().getTime();

System.out.println(a); // 1602243261784

System.currentTimeMillis

常用来计时, 单位是毫秒

// 使用 System.currentTimeMillis

// 主要用来计算时间差

public static void getDiffTime() {

try {

long start = System.currentTimeMillis();

Thread.sleep(1000);

long end = System.currentTimeMillis();

System.out.println(end - start);

} catch (Exception e) {

e.printStackTrace();

}

}

SimpleDateFormat

常用来解析和格式化日期

// SimpleDateFormat 常用来输出标准格式日期

// yyyy-MM-dd HH:mm:ss

public static void getFormatDate() {

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");

System.out.println(simpleDateFormat.format(new Date()));

}

public static void getParseDate() {

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");

try {

Date date = simpleDateFormat.parse("2020-02-02");

System.out.println(date);

} catch (Exception e) {

e.printStackTrace();

}

}

LocalDate

获得日期类型的时间, 并且获得年月日

// LocalDate 获得当前日期, 并且获得年. 月, 日

public static void getNowDate() {

LocalDate date = LocalDate.now();

System.out.println(date);

System.out.println(date.getDayOfMonth());

System.out.println(date.getMonthValue());

System.out.println(date.getYear());

// 可以format

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");

String formatDate = date.format(formatter);

System.out.println(formatDate);

}

LocalTime

获得当前的日期时间, 并且获得时,分,秒

// LocalTime, 获得当前的日期时间, 并且获得时,分,秒

public static void getNowTime() {

LocalTime time = LocalTime.now(); // 20:13:56.241

System.out.println(time);

System.out.println(time.getHour());

System.out.println(time.getMinute());

System.out.println(time.getSecond());

// 可以format

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm:ss");

String formatTime = time.format(formatter);

System.out.println(formatTime);

}

LocalDateTime

获得当前的日期时间, 并且获得年月日时分秒

// LocalDateTime, 获得当前的日期时间, 并且获得年月日时分秒

public static void getNowDateTime() {

LocalDateTime datetime = LocalDateTime.now();

System.out.println(datetime);

System.out.println(datetime.getYear());

System.out.println(datetime.getDayOfMonth());

System.out.println(datetime.getMonthValue());

System.out.println(datetime.getHour());

System.out.println(datetime.getMinute());

System.out.println(datetime.getSecond());

// format

DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

String formatDatetime = datetime.format(dateTimeFormatter);

System.out.println(formatDatetime); // 2020-07-17 09:22:54

}

获得指定时间类型的数据

可以使用parse解析输入的字符串

// 指定日期时间

public static void getTimeDefine() {

String time1 = "2020-02-02";

String time2 = "2020-02-02 15:03";

String time3 = "16:20:20";

LocalDate time1Parse = LocalDate.parse(time1);

System.out.println(time1Parse);

System.out.println(time1Parse.getDayOfMonth());

LocalDateTime time2Parse = LocalDateTime.parse(time2, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm"));

System.out.println(time2Parse);

System.out.println(time2Parse.getHour());

System.out.println(time2Parse.getSecond()); // 默认是0

// 解析之后再格式化输出

System.out.println(time2Parse.format(DateTimeFormatter.ofPattern("yyyy:MM:dd HH:mm:ss")));

LocalTime time3Parse = LocalTime.parse(time3);

System.out.println(time3Parse);

System.out.println(time3Parse.getHour());

System.out.println(time3Parse.format(DateTimeFormatter.ofPattern("HH:mm")));

}

或者使用of方法

public static void getTimeDefine2() {

LocalDateTime time1 = LocalDateTime.of(2020, 2, 3, 13, 2, 33);

System.out.println(time1);

System.out.println(time1.getYear());

System.out.println(time1.getSecond());

LocalDate time2 = LocalDate.of(2020, 2, 3);

System.out.println(time2);

System.out.println(time2.getDayOfMonth());

System.out.println(time2.getYear());

}

Duration

时间区间, 使用秒和纳秒衡量, 只能用DateTime

// 计算日期差

public static void getDiffDate() {

// Duration用秒和纳秒衡量时间, 所以只能用LocalDateTime

LocalDateTime date1 = LocalDateTime.parse("2020-02-02 00:00:00", DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));

LocalDateTime date2 = LocalDateTime.of(2020, 4, 2, 0, 0, 0);

Duration duration = Duration.between(date1, date2);

System.out.println(duration.toString()); // PT-744H

System.out.println(duration.toDays()); // 后 - 前

System.out.println(duration.toHours());

System.out.println(duration.toMillis());

}

Period

时间区间, 衡量年月日和几天之间的时间值

// 计算日期差Period

public static void getDiddDate2() {

// Period

// 计算间隔多少年月天, 以大单位先开始排, toTotalMonths可以获得总共间隔多少月

LocalDate date1 = LocalDate.of(2018, 2, 2);

LocalDate date2 = LocalDate.of(2020, 1, 10);

Period period = Period.between(date1, date2);

System.out.println(period.getYears());

System.out.println(period.getDays());

System.out.println(period.getMonths());

System.out.println(period.toTotalMonths());

System.out.printf("区间间隔%d年%d月%d天\n", period.getYears(), period.getMonths(), period.getDays());

}

toEpochDay 计算相差多少日

// 计算日期相差多少天

public static void getDiffDay() {

LocalDate date1 = LocalDate.of(2020, 2, 3);

LocalDate date2 = LocalDate.of(2020, 1, 19);

long date1EpochDay = date1.toEpochDay(); // 返回的是距离1970-01-01的天数

System.out.println(date1EpochDay);

long diffDays = date1.toEpochDay() - date2.toEpochDay();

System.out.println(diffDays);

}

日期相加减

// 日期相加减

public static void plusMinDay() {

LocalDate date1 = LocalDate.of(2020, 2, 3);

LocalDate date2 = date1.plusDays(3);

System.out.println(date2);

LocalDate date3 = date1.plusYears(2);

System.out.println(date3);

LocalDate date4 = date1.minusDays(10);

System.out.println(date4);

LocalDate date5 = date1.minusDays(-10);

System.out.println(date5);

}

时间, 日期, 日期时间之间的互相转化

// time, date, datetime之间互相转化

public static void dateToTimeStamp() {

// date => datetime asTime

LocalDate date1 = LocalDate.of(2020, 1, 2);

LocalDateTime time1 = date1.atTime(LocalTime.parse("06:30:20"));

LocalDateTime time2 = date1.atTime(LocalTime.of(6,30,30));

System.out.println(time1.toString());

System.out.println(time2.toString());

// time => datetime

LocalTime time6 = LocalTime.of(13, 13, 13);

LocalDateTime date3 = time6.atDate(LocalDate.parse("2020-02-02"));

System.out.println(date3);

// datetime => date / time

LocalDateTime time3 = LocalDateTime.of(2020, 2, 2, 13, 1, 1);

LocalDate date2 = time3.toLocalDate();

System.out.println(date2.toString());

LocalTime time4 = time3.toLocalTime();

System.out.println(time4);

}

时间类型和时间戳互相转化

// 转化为时间戳

public static void dateTimeToTimestamp() {

// datetime转时间戳

LocalDateTime time1 = LocalDateTime.of(2020,2,2,2,2,2);

long timestrap = time1.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();

System.out.println(timestrap); // 1580580122000 13位时间戳

// 时间戳转datetime

Instant instant = Instant.ofEpochMilli(1580580122000L);

LocalDateTime time2 = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());

System.out.println(time2.toString());

}