如何将Date转化为LocalDateTime
package cn.hutool.core.date;
public class LocalDateTimeUtil {
/**
* {@link Date}转{@link LocalDateTime}，使用默认时区
*
* @param date Date对象
* @return {@link LocalDateTime}
*/
public static LocalDateTime of(Date date) {
if (null == date) {
return null;
}
if (date instanceof DateTime) {
return of(date.toInstant(), ((DateTime) date).getZoneId());
}
return of(date.toInstant());
}
}
如何将LocalDateTime、LocalDate转化为Date
- 方案1
对纯原生的转化方式Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant())进行简单封装。即先使用TemporalAccessorUtil#toInstant(TemporalAccessor)将LocalDateTime转化为Instant（底层就是执行localDateTime.atZone(ZoneId.systemDefault()).toInstant()）
package cn.hutool.core.date;
public class TemporalAccessorUtil extends TemporalUtil{
/**
* {@link TemporalAccessor}转换为 {@link Instant}对象
*
* @param temporalAccessor Date对象
* @return {@link Instant}对象
* @since 5.3.10
*/
public static Instant toInstant(TemporalAccessor temporalAccessor) {
if (null == temporalAccessor) {
return null;
}
Instant result;
if (temporalAccessor instanceof Instant) {
result = (Instant) temporalAccessor;
} else if (temporalAccessor instanceof LocalDateTime) {
result = ((LocalDateTime) temporalAccessor).atZone(ZoneId.systemDefault()).toInstant();
} else if (temporalAccessor instanceof ZonedDateTime) {
result = ((ZonedDateTime) temporalAccessor).toInstant();
} else if (temporalAccessor instanceof OffsetDateTime) {
result = ((OffsetDateTime) temporalAccessor).toInstant();
} else if (temporalAccessor instanceof LocalDate) {
result = ((LocalDate) temporalAccessor).atStartOfDay(ZoneId.systemDefault()).toInstant();
} else if (temporalAccessor instanceof LocalTime) {
// 指定本地时间转换 为Instant，取当天日期
result = ((LocalTime) temporalAccessor).atDate(LocalDate.now()).atZone(ZoneId.systemDefault()).toInstant();
} else if (temporalAccessor instanceof OffsetTime) {
// 指定本地时间转换 为Instant，取当天日期
result = ((OffsetTime) temporalAccessor).atDate(LocalDate.now()).toInstant();
} else {
// issue#1891@Github
// Instant.from不能完成日期转换
//result = Instant.from(temporalAccessor);
result = toInstant(LocalDateTimeUtil.of(temporalAccessor));
}
return result;
}
}
再使用Date#from(Instant)
package java.util;
public class Date implements java.io.Serializable, Cloneable, Comparable<Date> {
/**
* Obtains an instance of {@code Date} from an {@code Instant} object.
* <p>
* {@code Instant} uses a precision of nanoseconds, whereas {@code Date}
* uses a precision of milliseconds. The conversion will truncate any
* excess precision information as though the amount in nanoseconds was
* subject to integer division by one million.
* <p>
* {@code Instant} can store points on the time-line further in the future
* and further in the past than {@code Date}. In this scenario, this method
* will throw an exception.
*
* @param instant the instant to convert
* @return a {@code Date} representing the same point on the time-line as
* the provided instant
* @exception NullPointerException if {@code instant} is null.
* @exception IllegalArgumentException if the instant is too large to
* represent as a {@code Date}
* @since 1.8
*/
public static Date from(Instant instant) {
try {
return new Date(instant.toEpochMilli());
} catch (ArithmeticException ex) {
throw new IllegalArgumentException(ex);
}
}
}
- 方案2
DateTime类继承于java.util.Date类，为Date类扩展了众多简便方法，这些方法多是DateUtil静态方法的对象表现形式，使用DateTime对象可以完全替代开发中Date对象的使用。
package cn.hutool.core.date;
public class DateUtil extends CalendarUtil {
/**
* {@link TemporalAccessor}类型时间转为{@link DateTime}<br>
* 始终根据已有{@link TemporalAccessor} 产生新的{@link DateTime}对象
*
* @param temporalAccessor {@link TemporalAccessor},常用子类： {@link LocalDateTime}、 LocalDate
* @return 时间对象
* @since 5.0.0
*/
public static DateTime date(TemporalAccessor temporalAccessor) {
return new DateTime(temporalAccessor);
}
}
- 示例
public class Test {
public static void main(String[] args) {
final LocalDateTime localDateTime = LocalDateTime.of(2022, 5, 9, 11, 36);
final Date date1 = Date.from(TemporalAccessorUtil.toInstant(localDateTime));
final DateTime date2 = DateUtil.date(localDateTime);
}
}
