問題描述

我需要解析以下形式的(德語)日期:

I need to parse (German) dates that come in the following form:

10. Jan. 18:14
8. Feb. 19:02
1. M?r. 19:40
4. Apr. 18:55
2. Mai 21:55
5. Juni 08:25
5. Juli 20:09
1. Aug. 13:42
[...]

如您所見，如果月份的字符數超過 4 個，則月份名稱會被刪減.更奇怪的是，不要問我為什么，盡管全名是 M?rz，但 3 月份縮短為 M?r..如何用 java.time 解析這個?(日期是根據創建日期列表的 android 設備的本地化格式化的.但是，我不會在 Android 上解析它)

As you can see, the month names are cut if the month has more than 4 characters. Even weirder, don't aks me why, the month of March is shortened to M?r. although the whole name is M?rz. How can I parse this with java.time? (The dates are formatted based on the localization of the android device that creates the list of dates. However, I'm not parsing it on Android)

我的方法是像這樣創建一個 DateTimeFormatter:

My approach was to create a DateTimeFormatter like this:

DateTimeFormatter.ofPattern("d. MMMM HH:mm").withLocale(Locale.GERMAN);
// or
DateTimeFormatter.ofPattern("d. MMMMM HH:mm").withLocale(Locale.GERMAN);

但是 MMMM 和 MMMMM 模式都不適合縮短的日期.當然，我可以使用以下模式 d.嗯.HH:mm 來匹配縮短的月份，但是我無法匹配 3 和 4 個字符的月份.我知道我可以有兩個格式化程序(MMM. 和 MMMMM)，但我寧愿有一個解決方案，我只有一個格式化程序，可能還有一個自定義語言環境或類似的東西.

But neither the MMMM nor the MMMMM pattern fit the dates that are shortened. I can, of course, have the following pattern d. MMM. HH:mm to match the shortened months, but then I can't match the 3 and 4 characters months. I am aware that I can have two formatters (MMM. and MMMMM) but I would rather have a solution where I have only one formatter and possibly a custom locale or something like this.

推薦答案

問題的答案是DateTimeFormatterBuilder 類和 appendText(TemporalField, Map) 方法.它允許任何文本在格式化或解析時與一個值關聯，從而有效而優雅地解決問題:

The answer to the problem is the DateTimeFormatterBuilder class and the appendText(TemporalField, Map) method. It allows any text to be associated with a value when formatting or parsing, which solves the problem effectively and elegantly:

Map<Long, String> monthNameMap = new HashMap<>();
monthNameMap.put(1L, "Jan.");
monthNameMap.put(2L, "Feb.");
monthNameMap.put(3L, "Mar.");
DateTimeFormatter fmt = new DateTimeFormatterBuilder()
    .appendPattern("d. ")
    .appendText(ChronoField.MONTH_OF_YEAR, monthNameMap)
    .appendPattern(" HH:mm")
    .parseDefaulting(ChronoField.YEAR, 2016)
    .toFormatter();

System.out.println(LocalDateTime.parse("10. Jan. 18:14", fmt));
System.out.println(LocalDateTime.parse("8. Feb. 19:02", fmt));

一些注意事項:

• monthNameMap 必須填寫所有 12 個月
• 格式化程序通常應分配給靜態最終常量，而不是一直創建
• 已添加 parseDefaulting(YEAR, 2016)，以便可以直接使用 LocalDateTime.parse(String, DateTimeFormatter).沒有它，就沒有年份，因此只能解析 TemporalAccessor (年份必須是閏年，以防解析 2 月 29 日)

• The monthNameMap must be populated with all 12 months
• The formatter should normally be assigned to a static final constant, rather than being created all the time
• The parseDefaulting(YEAR, 2016) has been added so that LocalDateTime.parse(String, DateTimeFormatter) can be used directly. Without it, there would be no year, and thus nothing more than a TemporalAccessor could be parsed (the year must be a leap year, in case 29th Feb is being parsed)

這篇關于如何使用 DateTimeFormatter 解析非標準月份名稱的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！