对DateFormat的操作之joda-time

采用的版本如下：

joda-time-2.1.jar

 

基于joda-time进行date format的操作代码如下：

		Calendar calendar = Calendar.getInstance();
		calendar.setTimeInMillis(System.currentTimeMillis());
		String pattern = "yyyy-MM-dd hh:mm:ss";

		DateTime dateTime = new DateTime(calendar);
		String dateStr = dateTime.toString(pattern);
		LOGGER.info("dateStr:" + dateStr);

		DateTime date = DateTimeFormat.forPattern(pattern).parseDateTime(dateStr);
		LOGGER.info("date:" + date.toDate());

根据pattern创建DateTimeFormatter ：

    public static DateTimeFormatter forPattern(String s)
    {
        return createFormatterForPattern(s);
    }

 具体的创建过程：

    private static DateTimeFormatter createFormatterForPattern(String s)
    {
        if(s == null || s.length() == 0)
            throw new IllegalArgumentException("Invalid pattern specification");
        DateTimeFormatter datetimeformatter = null;
        synchronized(cPatternedCache)
        {
            datetimeformatter = (DateTimeFormatter)cPatternedCache.get(s);
            if(datetimeformatter == null)
            {
                DateTimeFormatterBuilder datetimeformatterbuilder = new DateTimeFormatterBuilder();
                parsePatternTo(datetimeformatterbuilder, s);
                datetimeformatter = datetimeformatterbuilder.toFormatter();
                cPatternedCache.put(s, datetimeformatter);
            }
        }
        return datetimeformatter;
    }

 也就是先根据pattern从map中获取，如果没有的话那么build

那么我们看DateTimeFormatter是否线程安全的？

    private final DateTimePrinter iPrinter;
    private final DateTimeParser iParser;
    private final Locale iLocale;
    private final boolean iOffsetParsed;
    private final Chronology iChrono;
    private final DateTimeZone iZone;
    private final Integer iPivotYear;
    private final int iDefaultYear;

 没有static 符合线程安全条件，那么同样是线程安全的