java - 使用 DateTimeFormatterBuilder 将 String 解析为 LocalDateTime 时如何防止自动生成 'T' 字母

Question

我有这段代码可以将字符串双向解析为 LocalDateTime:

public class ConvertLocalDateToString {

private static final DateTimeFormatter CUSTOM_LOCAL_DATE;
static {
    CUSTOM_LOCAL_DATE = new DateTimeFormatterBuilder()
            .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD)
            .appendLiteral('-')
            .appendValue(MONTH_OF_YEAR, 2)
            .appendLiteral('-')
            .appendValue(DAY_OF_MONTH, 2)
            .appendLiteral(' ')
            .appendValue(HOUR_OF_DAY, 2)
            .appendLiteral(':')
            .appendValue(MINUTE_OF_HOUR, 2)
            .optionalStart()
            .appendLiteral(':')
            .appendValue(SECOND_OF_MINUTE, 2)
            .toFormatter();
}

public static void main(String[] args) {

    String str = "2020-02-18 15:04:30";
    LocalDateTime dateTime = LocalDateTime.parse(str, CUSTOM_LOCAL_DATE); //2020-02-18T15:04:30

    LocalDateTime addedDateTime = LocalDateTime.parse(dateTime.plusHours(10).format(CUSTOM_LOCAL_DATE.withZone(ZoneOffset.UTC)));
    System.out.println(addedDateTime);
    System.out.println(dateTime); //2020-02-18T15:04:30

}

我的假设是“T”字母是由 ISO-8601 格式自动生成的。这导致:

DateTimeParseException: Text '2020-02-18 15:04:30' could not be parsed at index 10

如何摆脱它？

Answer 1

System.out.println(dateTime) 与 System.out.println(String.valueOf(dateTime)) 相同。

String.valueOf(dateTime) 与 dateTime.toString() 相同，只是它可以处理 null 值。

在 LocalDateTime 上调用 toString() 是 documented为此:

Outputs this date-time as a String, such as 2007-12-03T10:15:30.

The output will be one of the following ISO-8601 formats:

• uuuu-MM-dd'T'HH:mm
• uuuu-MM-dd'T'HH:mm:ss
• uuuu-MM-dd'T'HH:mm:ss.SSS
• uuuu-MM-dd'T'HH:mm:ss.SSSSSS
• uuuu-MM-dd'T'HH:mm:ss.SSSSSSSSS

The format used will be the shortest that outputs the full value of the time where the omitted parts are implied to be zero.

如果您需要不同的格式，请调用format(DateTimeFormatter formatter) .

<小时/>

那么，回答你的问题:

My assumption is 'T' letter is auto-generated by ISO-8601 format.

T 并不比 - 和 : 字符更自动生成。

How do I get rid of it?

调用format(...)并指定您想要的格式，例如

System.out.println(dateTime.format(DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss")));