将UTC字符串日期转换为日期格式 [英] Convert UTC string date to date format

问题描述

如何转换字符串 2020-09-02T12：22：53.9迄今Java中的格式2020-09-02T12：22：53.9？

How to convert string "2020-09-02T12:22:53.9" to date format 2020-09-02T12:22:53.9 in java?

String dateString = "2020-09-02T12:22:53.9";
String tz = "America/Mexico_City";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-dd-mm hh:mm:ss.S");
ZoneId zoneId = ZoneId.of(tz);
Instant instant = Instant.parse(dateString);
ZonedDateTime dateTimeInTz =ZonedDateTime.ofInstant(instant, zoneId);
System.out.println(dateTimeInTz.format(dtf));

此代码引发 java.time.format.DateTimeParseException：文本'2020-09-02T12 ：22：53.9'无法在索引21 中从行 Instant Instant = Instant.parse（dateString）; 解析。

This code throws a java.time.format.DateTimeParseException: Text '2020-09-02T12:22:53.9' could not be parsed at index 21 form the line Instant instant = Instant.parse(dateString);.

推荐答案

您的格式不正确。您在本月中使用了 mm 而不是 MM 。另外，您还错过了格式中的文字 T 。请注意，您需要在24小时格式时间内使用 HH 。

Your format is not correct. You have used mm, instead of MM, for the month. Also, you have missed the literal T in the format. Note that you need to use HH for 24-hours format time.

由于日期时间字符串中没有时间，区域信息，您必须将日期时间字符串解析为 LocalDateTime ，然后使用 LocalDateTime＃atZone 进行转换设置为 ZonedDateTime （如果您完全需要 ZonedDateTime ），如下所示：

Since your date-time string does not have a time-zone information, you will have to parse the date-time string to LocalDateTime and then use LocalDateTime#atZone to convert it to ZonedDateTime (if at all you need ZonedDateTime) as shown below:

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        String dateString = "2020-09-02T12:22:53.9";

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

        String tz = "America/Mexico_City";
        ZoneId zoneId = ZoneId.of(tz);

        // Parse the given date-time string to LocalDateTime
        LocalDateTime ldt = LocalDateTime.parse(dateString, dtf);

        // Convert the LocalDateTime to ZonedDateTime
        ZonedDateTime dateTimeInTz = ldt.atZone(zoneId);

        // Display ZonedDateTime in its default format
        System.out.println(dateTimeInTz);

        // Display ZonedDateTime in your custom format
        System.out.println(dateTimeInTz.format(dtf));
    }
}

输出：

2020-02-09T12:22:53.900-06:00[America/Mexico_City]
2020-09-02T12:22:53.9

或者，您可以将 ZoneId 与 DateTimeFormatter 本身，然后可以将给定的日期时间字符串直接解析为 ZonedDateTime ，如下所示：

Alternatively, you can use the ZoneId with DateTimeFormatter itself and then you can parse the given date-time string directly into ZonedDateTime as shown below:

import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        String dateString = "2020-09-02T12:22:53.9";

        String tz = "America/Mexico_City";
        ZoneId zoneId = ZoneId.of(tz);

        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-dd-MM'T'HH:mm:ss.S").withZone(ZoneId.of(tz));

        // Parse the given date-time string into ZonedDateTime
        ZonedDateTime dateTimeInTz = ZonedDateTime.parse(dateString, dtf);

        // Display ZonedDateTime in its default format
        System.out.println(dateTimeInTz);

        // Display ZonedDateTime in your custom format
        System.out.println(dateTimeInTz.format(dtf));
    }
}

输出：

2020-02-09T12:22:53.900-06:00[America/Mexico_City]
2020-09-02T12:22:53.9

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