java DateTimeFormatter无法按预期工作

Question

我必须将日期时间字符串转换为分区日期时间对象。我使用了DateTimeFormatter来阅读模式。根据documentation，模式中的“Z”可以接受如下格式：

• +/-万
• +/-00:00

但是分区时间。parse（myDate，格式化程序）仅适用于第一种情况；相反，在第二种情况下，代码生成一个异常

Execution exception[[DateTimeParseException: Text '2020-06-22T16:00:00.000+00:00' could not be parsed at index 23]]

我正在使用Java8。举例及；代码：

"2020-06-08T12:59:10.288+0000" **work**
"2020-06-08T12:59:10.288+00:00" **doesn't work**

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ");

ZonedDateTime dateConvertedUTC = ZonedDateTime.parse(dateTime, formatter);
LocalDateTime dateConverted = dateConvertedUTC.withZoneSameInstant(ZoneId.of("Europe/Rome")).toLocalDateTime();

我做错了什么？ 谢谢

Answer 1

您为时区指定了Z，这就是2020-06-08T12:59:10.288+0000起作用的原因

但是如果你想解析2020-06-08T12:59:10.288+00:00，你的格式必须是

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ");

您可以在JavaDoc中找到：

Offset Z: This formats the offset based on the number of pattern letters. One, two or three letters outputs the hour and minute, without a colon, such as '+0130'. The output will be '+0000' when the offset is zero. Four letters outputs the full form of localized offset, equivalent to four letters of Offset-O. The output will be the corresponding localized offset text if the offset is zero. Five letters outputs the hour, minute, with optional second if non-zero, with colon. It outputs 'Z' if the offset is zero. Six or more letters throws IllegalArgumentException.

Answer 2

您确实需要为日期时间字符串2020-06-08T12:59:10.288+00:00定义一种格式。它已经在default format of OffsetDateTime中了

import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;

public class Main {
    public static void main(String[] args) {
        OffsetDateTime odt = OffsetDateTime.parse("2020-06-08T12:59:10.288+00:00");
        System.out.println(odt);

        // Get ZonedDateTime in the desired time-zone from OffsetDateTime
        ZonedDateTime zdt = odt.atZoneSameInstant(ZoneId.of("Europe/Rome"));

        // Get LocalDateTime from ZonedDateTime
        LocalDateTime ldt = zdt.toLocalDateTime();
        System.out.println(ldt);
    }
}

输出：

2020-06-08T12:59:10.288Z
2020-06-08T14:59:10.288

注意：从ZonedDateTime到LocalDateTime的转换丢弃了有价值的信息，即时区。因此，只有在确定业务逻辑不需要时区信息时，才应该执行此转换