使用时区java将字符串转换为适当的日期 [英] Convert string to appropriate date with timezone java

问题描述

我正在使用时区，我想将其转换为另一个时区，例如我有时间'GMT-06：00'的日期'3/15/2013 3:01:53 PM'。我想在GMT-05：00时区转换。我有很多的搜索，我很困惑，实际上日期是如何工作的。如何应用时区到目前为止。我尝试使用SimpleDateFormat，Calender和偏移量。

I am Having Date with it's timezone, I want to convert it to another Timezone, E.g. I have Date '3/15/2013 3:01:53 PM' which is in TimeZone 'GMT-06:00'. I want to convert this in 'GMT-05:00' timezone. I have search lot, and I am confuse about How actually Date is working. How to Apply timezone to date. I have try with SimpleDateFormat, Calender and also with offset.

DateFormat df = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss aaa XXX");
df.setTimeZone(TimeZone.getTimeZone("GMT")); 
Date dt = null;
        try
        {
            dt = df.parse("3/15/2013 3:01:53 PM -06:00");
        }catch (ParseException e) {
        e.printStackTrace();
    } 
String newDateString = df.format(dt);
System.out.println(newDateString);

它返回输出
03/15/2013 09:01 ：53 AM Z 。
我猜应该是
03/15/2013 09:01:53 PM Z ，因为在GMT-06：00时区的时间，所以在GMT时间应该是HH + 6。我想要日期在yyyy-MM-dd HH：mm：ss格式，其中HH在24小时内。请帮助我举个例子。提前致谢。

It returns output 03/15/2013 09:01:53 AM Z. I guess it should be 03/15/2013 09:01:53 PM Z, because time in 'GMT-06:00' timezone, so it should be HH+6 to get time in GMT. I want Date in "yyyy-MM-dd HH:mm:ss" format where HH is in 24 hour.Please Help me with example. Thanks in advance.

编辑：

我使用SimpleDateFormat将字符串转换为日期

I am converting the string into date using SimpleDateFormat

DateFormat df = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss aaa");
    Date dt = null;
    try {
        dt = df.parse("3/15/2013 3:01:53 PM");
    } catch (ParseException e) {
        e.printStackTrace();
    }

现在，正如你所说，我指定了Calender，我的日期属于到GMT-06：00'时区，并设置我的日期

Now, as you say, I am specify to Calender that my date is belong to 'GMT-06:00' timezone and set my date,

Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("GMT-6"));
cal.setTime(dt);

现在，我要告诉日历我想要在GMT中的日期

Now, I am telling calender that i want date in 'GMT'

cal.setTimeZone (TimeZone.getTimeZone("GMT"));

System.out.println（cal.getTime（））;

System.out.println(cal.getTime());

OutPut：

Fri Mar 15 03:01:53 CDT 2013

请知道我是否出错。

推荐答案

您需要两个格式对象，一个用于解析，另一个用于打印，因为您使用两个不同的时区，请参见此处：

You need TWO format objects, one for parsing and another one for printing because you use two different timezones, see here:

// h instead of H  because of AM/PM-format
DateFormat parseFormat = new SimpleDateFormat("M/dd/yyyy hh:mm:ss aaa XXX"); 
Date dt = null;
try {
  dt = parseFormat.parse("3/15/2013 3:01:53 PM -06:00");
}catch (ParseException e) {
  e.printStackTrace();
} 

DateFormat printFormat = new SimpleDateFormat("M/dd/yyyy hh:mm:ss aaa XXX"); 
printFormat.setTimeZone(TimeZone.getTimeZone("GMT-05")); 
String newDateString = printFormat.format(dt);
System.out.println(newDateString);

输出：3/15/2013 04:01:53 PM -05：00

Output: 3/15/2013 04:01:53 PM -05:00

如果你想要HH：mm：ss（24小时格式），那么你只需要替换

If you want HH:mm:ss (24-hour-format) then you just replace

hh:mm:ss aaa 

by

HH:mm:ss

对其他问题的评论：

A java.util.Date 没有内部时区，总是指定UTC。您不能在此对象内更改它。对于格式化的字符串可能进行时区转换，但是如我的代码示例（您想转换为GMT-05区域）所示。

A java.util.Date has no internal timezone and always refers to UTC by spec. You cannot change it inside this object. A timezone conversion is possible for the formatted string, however as demonstrated in my code example (you wanted to convert to zone GMT-05).

然后，该问题切换到以ISO格式打印 Date -object的新要求，使用UTC时区（符号Z）。这可以通过用yyyy-MM-dd'T'HH：mm：ssXXX替换模式进行格式化，并将printFormat的时区显式设置为GMT + 00。您应该澄清您真正想要的格式化输出。

The question then switches to the new requirement to print the Date-object in ISO-format using UTC timezone (symbol Z). This can be done in formatting by replacing the pattern with "yyyy-MM-dd'T'HH:mm:ssXXX" and explicitly setting the timezone of printFormat to GMT+00. You should clarify what you really want as formatted output.

关于 java.util.GregorianCalendar ：设置时区为正在以程序方式更改日历对象，因此影响方法调用，如 calendar.get（Calendar.HOUR_OF_DAY）。这与格式化无关！

About java.util.GregorianCalendar: Setting the timezone here is changing the calendar-object in a programmatical way, so it affects method calls like calendar.get(Calendar.HOUR_OF_DAY). This has nothing to do with formatting however!

这篇关于使用时区java将字符串转换为适当的日期的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！