java时间戳与LocalDateTime常用转换方式

1 Date、LocalDate、LocalTime、LocalDateTime与时间戳的转换
在时间转换中，ZoneOffset表示偏移量，北京时间是+8，一般写为：ZoneOffset.of("+8")，也可以写为ZoneOffset.ofHours(8)

认识一下Date、LocalDate、LocalDateTime与时间戳

public static void main(String[] args) {

   // Fri Jan 06 14:09:40 CST 2023
   System.out.println(new Date());

   // 2023-01-06
   System.out.println(LocalDate.now());

   // 14:09:40.628
   System.out.println(LocalTime.now());

   // 2023-01-06T14:09:40.628
   System.out.println(LocalDateTime.now());

   // 1672985380628
   System.out.println(System.currentTimeMillis());

}

1.1 获取系统当前时间戳
long millis = System.currentTimeMillis();

1.2 LocalDate转Date
LocalDate nowLocalDate = LocalDate.now();
Date date = Date.from(nowLocalDate.atStartOfDay(ZoneId.systemDefault()).toInstant())

1.3 LocalTime转Date
public void LocalTimeToUdate() {
LocalTime localTime = LocalTime.now();
LocalDate localDate = LocalDate.now();
LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
ZoneId zone = ZoneId.systemDefault();
Instant instant = localDateTime.atZone(zone).toInstant();
java.util.Date date = Date.from(instant);
}

1.4 LocalDateTime转Date
LocalDateTime localDateTime = LocalDateTime.now();
Date date = Date.from(localDateTime.atZone(ZoneOffset.ofHours(8)).toInstant());

1.6 Date转LocalDate
Date date = new Date();
LocalDate localDate = date.toInstant().atZone(ZoneOffset.ofHours(8)).toLocalDate();

1.7 Date转LocalDateTime
Date date = new Date();
LocalDateTime localDateTime = date.toInstant().atZone(ZoneOffset.ofHours(8)).toLocalDateTime();

1.8 LocalDate转时间戳
LocalDate localDate = LocalDate.now();
long timestamp = localDate.atStartOfDay(ZoneOffset.ofHours(8)).toInstant().toEpochMilli();

1.9 LocalDateTime转时间戳
LocalDateTime localDateTime = LocalDateTime.now();
long timestamp = localDateTime.toInstant(ZoneOffset.ofHours(8)).toEpochMilli();

2 使用LocalDate、LocalTime、LocalDateTime做时间偏移
2.1 获取当月最后一天23:59:59
public static void main(String[] args) {

   // 2023-01-31
   final LocalDate lastDate = LocalDate.now().with(TemporalAdjusters.lastDayOfMonth());
   System.out.println(lastDate);

   // 2023-01-31T13:46:56.177
   final LocalDateTime lastDateTime = LocalDateTime.now().with(TemporalAdjusters.lastDayOfMonth());
   System.out.println(lastDateTime);

   // 2023-01-31T23:59:59
   final LocalDateTime lastDateTime2 = LocalDateTime.parse(lastDate + "T23:59:59");
   System.out.println(lastDateTime2);

}

3 时间戳转和LocalDateTime和Date
3.1 时间戳转LocalDateTime
秒时间戳转为LocalDateTime

public static void main(String[] args) {
//获得时间戳
long second = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).getEpochSecond();
// 将时间戳转为当前时间
LocalDateTime localDateTime = LocalDateTime.ofEpochSecond(second, 0, ZoneOffset.ofHours(8));
// 2020-02-03T13:30:44
System.out.println(localDateTime);
}

毫秒时间戳转为LocalDateTime

public static void main(String[] args) {
//获得时间戳
long milliseconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
// 将时间戳转为当前时间
LocalDateTime localDateTime = Instant.ofEpochMilli(milliseconds).atZone(ZoneOffset.ofHours(8)).toLocalDateTime();
// 2020-02-03T13:38:35.799
System.out.println(localDateTime);
}

3.2 时间戳转LocalDate
秒时间戳转为LocalDate

public static void main(String[] args) {
//获得时间戳
long seconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).getEpochSecond();
// 将时间戳转为当前时间
LocalDate localDate = Instant.ofEpochSecond(seconds).atZone(ZoneOffset.ofHours(8)).toLocalDate();
// 2020-02-03
System.out.println(localDate);
}

毫秒时间戳转为LocalDate

public static void main(String[] args) {
//获得时间戳
long milliseconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
// 将时间戳转为当前时间
LocalDate localDate = Instant.ofEpochMilli(milliseconds).atZone(ZoneOffset.ofHours(8)).toLocalDate();
// 2020-02-03
System.out.println(localDate);
}

4 LocalDateTime做时间偏移
import java.time.LocalDateTime;

public class Main {
public static void main(String[] args) {
// 获取当前时间
LocalDateTime now = LocalDateTime.now();
System.out.println("当前时间: " + now);

// 偏移三天后的时间
LocalDateTime future = now.plusDays(3);
System.out.println("三天后的时间: " + future);
}
}

java时间戳与LocalDateTime常用转换方式

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