JodaTime - 将字符串直接传递给DateTime的构造函数 [英] JodaTime-Passing a string directly to DateTime's constructor

问题描述

我在CEST时区（+2），我有一些困难了解JodaTime如何存储DateTime。代码如下：

I'm on CEST timezone (+2) and I'm having some difficulties understanding how JodaTime stores DateTime. Take this code:

String timeString = "2012-09-10T13:30:00+01:00";
DateTime ddateTime = new DateTime(timeString);
DateTime dtLisbon = ddateTime.withZone(DateTimeZone.forID("Europe/Lisbon"));

运行后，变量获取以下值：

After running, the variables get the following values:

timeString = '2012-09-10T13:30:00+01:00'
ddateTime = '2012-09-10T14:30:00.000+02:00'
dtLisbon = '2012-09-10T13:30:00.000+01:00'

为什么JodaTime不将ddateTime设置为我发送的确切字符串？我总是需要调用.withZone方法才能获得正确的时间？

Why doesn't JodaTime set ddateTime to the exact string that I'm sending? Do I always need to call .withZone method to get the right instant?

谢谢

推荐答案

您应该调用一个 DateTime 构造函数，该构造函数需要一个 DateTimeZone ：

You should be calling a DateTime constructor that takes a DateTimeZone like so:

new DateTime(timeString, DateTimeZone.forID("Europe/Lisbon"));

如果你逐步通过Joda的通话，我强烈推荐，如何将所有片段组合在一起，您将看到调用链：

If you step through the calls Joda is making, which I highly recommend so you can get a feel for how all the pieces fit together, you'll see that the call chain goes:

DateTime(Object)
  -> BaseDateTime(Object, Chronology)
    -> AbstractConverter.getChronology(Object, Chronology)
      -> DateTimeUtils.getChronology(Chronology)
        -> ISOChronology.getInstance()
          -> DateTimeZone.getDefault()
            -> System.getProperty("user.timezone")

这就是为什么 ddateTime 结束为UTC + 2，这是您的时区，当您不提供 DateTimeZone 而不是UTC + 1，区域。

So that's why ddateTime ends up being UTC+2, which is your time zone, when you don't provide a DateTimeZone instead of UTC+1, which is the time zone in the string you provided.

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