LocalDateTime用法大全

朱雀 2023-07-02 11:22 5阅读 0赞

# 常规使用 #

LocalDateTime now = LocalDateTime.now();   // 2020-01-29T14:35:51.207
    int year = now.getYear();                  // 2020
    Month month = now.getMonth();              // JANUARY
    int monthValue = now.getMonthValue();      // 1
    int dayOfYear = now.getDayOfYear();        // 29
    int dayOfMonth = now.getDayOfMonth();      // 29
    DayOfWeek dayOfWeek = now.getDayOfWeek();  // WEDNESDAY
    int dayOfWeekValue = dayOfWeek.getValue(); // 3
    int hour = now.getHour();                  // 14
    int minute = now.getMinute();              // 35
    int second = now.getSecond();              // 51
    
    long seconds = Instant.now().getEpochSecond();    // 秒时间戳(10位)
    long milliSeconds = Instant.now().toEpochMilli(); // 毫秒时间戳(13位)
    
    LocalDateTime dateTimeFromSecond = LocalDateTime.ofInstant(
        Instant.ofEpochSecond(seconds), ZoneOffset.ofHours(8)
    );  // 秒转datetime
    
    LocalDateTime dateTimeFromMilliSecond = LocalDateTime.ofInstant(
        Instant.ofEpochMilli(milliSeconds), ZoneOffset.ofHours(8)
    ); // 毫秒转datetime

# 各种转换 #

String format = LocalDateTime.now().format(
        DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
    );  // datetime转字符串
    
    LocalDateTime dateTime = LocalDateTime.parse(
        format,
        DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
    );  // 字符串转datetime
    
    Date date = Date.from(dateTime.toInstant(ZoneOffset.ofHours(8)));                             // datetime转date
    LocalDateTime fromDate = date.toInstant().atOffset(ZoneOffset.ofHours(8)).toLocalDateTime();  // date转datetime

# 自定义日期 / 日期加减 #

LocalDateTime dateTime = LocalDateTime.of(2020, 1, 29, 14, 35, 51); // 2020-01-29T14:35:51
    
    LocalDateTime localDateTime1 = dateTime.minusSeconds(1);            // 2020-01-29T14:35:50
    LocalDateTime localDateTime2 = dateTime.minusMinutes(1);            // 2020-01-29T14:34:51
    LocalDateTime localDateTime3 = dateTime.minusHours(1);              // 2020-01-29T13:35:51
    LocalDateTime localDateTime4 = dateTime.minusDays(1);               // 2020-01-28T14:35:51
    LocalDateTime localDateTime5 = dateTime.minusWeeks(1);              // 2020-01-22T14:35:51
    LocalDateTime localDateTime6 = dateTime.minusMonths(1);             // 2019-12-29T14:35:51
    LocalDateTime localDateTime7 = dateTime.minusYears(1);              // 2019-01-29T14:35:51

> 增加的为对应的plus函数，如`dateTime.plusSeconds(1)`

# 比较日期 #

LocalDateTime now = LocalDateTime.now();     // 2020-01-29T14:35:51.207
    LocalDateTime yesterday = now.minusDays(1);  // 2020-01-28T14:35:51.207
    boolean after = now.isAfter(yesterday);      // true
    boolean before = now.isBefore(yesterday);    // false
    boolean equal = now.isEqual(yesterday);      // false

# 其他类 #

## LocalDate日期 ##

LocalDate dateNow = LocalDate.now();        // 2020-01-29
    LocalDate date = LocalDate.of(2020, 1, 29); // 2020-01-29

## LocalTime时间 ##

LocalTime timeNow = LocalTime.now();       // 14:35:51.207
    LocalTime time = LocalTime.of(23, 59, 59); // 23:59:59

## LocalDateTime日期时间 ##

LocalDateTime dateTimeNow = LocalDateTime.now();                    // 2020-01-29T14:35:51.207
    LocalDateTime dateTime = LocalDateTime.of(2020, 1, 29, 23, 59, 59); // 2020-01-29T23:59:59

## Instant时刻 ##

long second = Instant.now().getEpochSecond();          // 1580279751
    long milliSecond = Instant.now().toEpochMilli();       // 1580279751000
    Instant instant1 = Instant.ofEpochSecond(second);     // 2020-01-29T14:35:51Z
    Instant instant2 = Instant.ofEpochMilli(milliSecond); // 2020-01-29T14:35:51.207Z

## Duration时间差 ##

Duration duration = Duration.between(
        LocalDateTime.now(), LocalDateTime.now().plusDays(1)
    );  // PT24H
    long seconds = duration.getSeconds();             // 86400
    long seconds2 = duration.get(ChronoUnit.SECONDS); // 86400
    
    Duration ofDays = Duration.ofDays(1);             // PT24H
    Duration ofHours = Duration.ofHours(1);           // PT1H
    Duration ofMinutes = Duration.ofMinutes(1);       // PT1M
    Duration ofSeconds = Duration.ofSeconds(1);       // PT1S

## Period时间段 ##

Period between = Period.between(
        LocalDate.of(2020, 1, 22), LocalDate.of(2020, 2, 9)
    ); // P18D
    int year = between.getYears();   // 0
    int month = between.getMonths(); // 0
    int day = between.getDays();     // 18
    
    Period period = Period.of(1, 2, 3); // P1Y2M3D
    long years = period.get(ChronoUnit.YEARS);            // 1
    long months = period.get(ChronoUnit.MONTHS);          // 2
    long days = period.get(ChronoUnit.DAYS);              // 3

## Clock时钟 ##

Clock clock1 = Clock.system(ZoneOffset.ofHours(8));  // SystemClock[+08:00]
    Clock clock2 = Clock.systemUTC();                    // SystemClock[Z]
    
    long millis1 = clock1.millis();      // 1582285924008
    long millis2 = clock2.millis();      // 1582285924008
    Instant instant1 = clock1.instant(); // 2020-02-21T11:54:58.427Z
    Instant instant2 = clock2.instant(); // 2020-02-21T11:54:58.428Z