Java Convert LocalDateTime to Date – Java 147

Post author:若雪
Post published:2023-07-21
Post category:RD / Java / Java Conversion / Java Conversion Datetime
Post comments:0 Comments
Post last modified:2023-10-12

內容目錄

Java Convert LocalDateTime to Date

將 LocalDate 轉換為 Date 實例的方法，簡單來說過程如： LocalDate -> ZonedDateTime -> Instant -> java.util.Date 這些步驟等， Java LocalDateTime Date 任務是將該 LocalDateTime 轉換為 Date ，本篇增加了範例，並透過單元測試來驗證產出結果。

檔案目錄

./
   +- src
       +- test
       |   +- org
       |       +- ruoxue
       |           +- java_147
       |               +- conversion
       |                   +- datetime
       |                       +- LocalDateTimeToDateTest.java

單元測試

Java LocalDateTime to Date 提供 LocalDateTime 轉換成 Date 等操作。

toDate

Java LocalDateTime to Date 使用 atStartOfDay 轉換成 Date 。

	@Test
	public void toDate() {
		ZoneId zone = ZoneId.of("Asia/Sakhalin");
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		ZonedDateTime zonedDateTime = localDateTime.atZone(zone);
		Instant instant = zonedDateTime.toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Mon Apr 03 21:00:00 CST 2023", date.toString());
	}

Mon Apr 03 21:00:00 CST 2023

toDateWithToInstant

Java LocalDateTime to Date 使用 toInstant 轉換成 Date 。

	@Test
	public void toDateWithToInstant() {
		ZoneId zone = ZoneId.of("Etc/GMT-11");
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		ZonedDateTime zonedDateTime = localDateTime.atZone(zone);
		Instant instant = zonedDateTime.toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Mon Apr 03 21:00:00 CST 2023", date.toString());
	}

Mon Apr 03 21:00:00 CST 2023

toDateWithValueOf

Java LocalDateTime to Date 使用 valueOf 轉換成 Date 。

	@Test
	public void toDateWithValueOf() {
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		String value = localDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
		Instant instant = Timestamp.valueOf(value).toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Tue Apr 04 00:00:00 CST 2023", date.toString());
	}

Tue Apr 04 00:00:00 CST 2023

LocalDateTimeToDateTest.java

Convert LocalDateTime to Date in Java 新增單元測試，驗證是否符合預期。

package org.ruoxue.java_147.conversion.datetime;

import static org.junit.Assert.*;

import java.sql.Timestamp;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;

import org.junit.Test;

public class LocalDateTimeToDate {

	@Test
	public void toDate() {
		ZoneId zone = ZoneId.of("Asia/Sakhalin");
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		ZonedDateTime zonedDateTime = localDateTime.atZone(zone);
		Instant instant = zonedDateTime.toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Mon Apr 03 21:00:00 CST 2023", date.toString());
	}

	@Test
	public void toDateWithToInstant() {
		ZoneId zone = ZoneId.of("Etc/GMT-11");
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		ZonedDateTime zonedDateTime = localDateTime.atZone(zone);
		Instant instant = zonedDateTime.toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Mon Apr 03 21:00:00 CST 2023", date.toString());
	}

	@Test
	public void toDateWithValueOf() {
		LocalDateTime localDateTime = LocalDateTime.of(2023, 4, 4, 0, 0, 0);
		String value = localDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
		Instant instant = Timestamp.valueOf(value).toInstant();

		Date date = Date.from(instant);
		System.out.println(date);
		assertEquals("Tue Apr 04 00:00:00 CST 2023", date.toString());
	}
}

心得分享

LocalDateTime to Date in Java 將 LocalDate 轉換為 Date，在日期後附加時間和時區信息，轉換步驟如下： 1. 取得時區，以便可以將時區資訊附加到日期，2. 調用 atStartOfDay() 以便可以將時間附加到日期， 3. 本地日期 + atStartOfDay() + 時區 + toInstant()， Convert LocalDateTime to Date in Java 提供將 LocalDateTime 實例轉換為 Date 實例的多種方法。