java - 如何从 SQL 日期时间 UTC 转换为 LocalDateTime 并再次转换回来

Question

代码应该从数据库中获取日期和时间，将其标记为 UTC(或者也许它应该已经知道它是 UTC？)，将其转换为本地时区，然后将日期和时间作为时间戳返回.

目前代码仅打印出数据库中的日期/时间并将本地时间保存到数据库中。

我对代码的解释是否错误？我是否缺少转换时间的步骤？

感谢您的任何额外帮助

package Utils;

import java.sql.Date;
import java.sql.Timestamp;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;


public class DateTimeConverter {

    public static Timestamp toLocalDateTime(Timestamp utc){
        //identify as UTC
        ZonedDateTime utcZonedDateTime = ZonedDateTime.ofInstant(utc.toInstant(), ZoneId.of("UTC"));
        Instant timestamp = utcZonedDateTime.toInstant();
        //set the timestamp to the systems default zone
        ZonedDateTime utcToLocal = timestamp.atZone(ZoneId.systemDefault());

        System.out.println(Timestamp.from(utcToLocal.toInstant()));

        return Timestamp.from(utcToLocal.toInstant());
    }

    public static Timestamp toUTC(Timestamp ldt){
        //identify as systems default zoneid
        ZonedDateTime localZDT = ZonedDateTime.ofInstant(ldt.toInstant(), ZoneId.systemDefault());
        Instant timestamp = localZDT.toInstant();
        //set the timestamp to UTC zoneid
        ZonedDateTime localToUTC = timestamp.atZone(ZoneId.of("UTC"));

        System.out.println(Timestamp.from(localToUTC.toInstant()));

        return Timestamp.from(localToUTC.toInstant());

    }

}

Answer 1

    public static Timestamp toLocalDateTime(Timestamp utc){

        LocalDateTime ldt = utc.toLocalDateTime();
        ZonedDateTime zdt = ldt.atZone(ZoneId.of("UTC"));
        ZonedDateTime newZdt = zdt.withZoneSameInstant(ZoneId.systemDefault());
        LocalDateTime newLdt = newZdt.toLocalDateTime();

        return Timestamp.valueOf(newLdt);

    }

    public static Timestamp toUTC(Timestamp ts){

        LocalDateTime ldt = ts.toLocalDateTime();
        ZonedDateTime zdt = ldt.atZone(ZoneId.systemDefault());
        ZonedDateTime newZdt = zdt.withZoneSameInstant(ZoneId.of("UTC"));
        LocalDateTime newLdt = newZdt.toLocalDateTime();

        return Timestamp.valueOf(newLdt);

    }