java 来自 joda 时间 DateTimeFormatter 的模式字符串？
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Pattern String from a joda-time DateTimeFormatter?
提问by Synesso
Is it possible to get the pattern string from a joda-time DateTimeFormatter?
是否可以从 joda-time DateTimeFormatter 获取模式字符串？
DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyyMMdd");
String originalPattern = formatter. ???
回答by gutch
Joda Time does not provide a way to get the original pattern from a DateTimeFormatter. One reason is probably that a DateTimeFormatter wasn't necessarily created from a pattern; for example DateTimeFormat.forStyle()does not use patterns at all.
Joda Time 不提供从 DateTimeFormatter 获取原始模式的方法。一个原因可能是 DateTimeFormatter 不一定是从模式创建的；例如DateTimeFormat.forStyle()根本不使用模式。
However if you always use patterns, then you could wrap the DateTimeFormatclass to record the pattern when the DateTimeFormatteris constructed. That way you can look it up later with a simple static method. For example:
但是，如果您总是使用模式，那么您可以包装DateTimeFormat类以在DateTimeFormatter构造时记录模式。这样你以后就可以用一个简单的静态方法来查找它。例如：
public class ReversableDateTimeFormat {
private static final Map<DateTimeFormatter, String> patternHistory = new HashMap<DateTimeFormatter, String>();
public static DateTimeFormatter forPattern(String pattern) {
DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern(pattern);
patternHistory.put(dateTimeFormatter, pattern);
return dateTimeFormatter;
}
public static String getPattern(DateTimeFormatter dateTimeFormatter) {
return patternHistory.get(dateTimeFormatter);
}
}
Then you can do this:
然后你可以这样做：
DateTimeFormatter formatter = ReversableDateTimeFormat.forPattern("yyyyMMdd");
String originalPattern = ReverseableDateTimeFormat.getPattern(formatter);
