本地日期和放大器;时间UTC，然后UTC当地的日期和放大器;时间 [英] Local date & time to UTC and then UTC to local date & time

问题描述

我想现场的时间转换为UTC，然后向UTC时间语言环境。但我没有得到的结果。

I am trying to convert locale time to UTC, and then UTC to locale time. But I am not getting the result.

public class DateDemo
{

public static void main(String args[])
{
    DateFormat dateFormatter = 
               DateFormat.getDateTimeInstance
                 (DateFormat.SHORT, DateFormat.SHORT, Locale.getDefault());

    TimeZone.setDefault(TimeZone.getDefault());

    SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("dd/MM/yyyy");
    SimpleDateFormat simpleTimeFormatter = new SimpleDateFormat("hh:mm:ss a");

    Date today = new Date();
    String localeFormattedInTime = dateFormatter.format(today);

    try
    {
        Date parsedDate = dateFormatter.parse(localeFormattedInTime);
        System.out.println("Locale:" + localeFormattedInTime);
        System.out.println("After parsing a date: " + parsedDate);

        simpleDateFormatter.setTimeZone(TimeZone.getDefault());
        simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

        String date = simpleDateFormatter.format(today);
        String time = simpleTimeFormatter.format(today);
        System.out.println("Today's only date: " + date);
        System.out.println("Today's only time: " + time);

        //// Locale to UTC converting

        simpleDateFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
        simpleTimeFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));

        String utcDate = simpleDateFormatter.format(today);
        String utcTime = simpleTimeFormatter.format(today);
        System.out.println("Convert into UTC's date: " + utcDate);
        System.out.println("Convert into UTC's only time: " + utcTime);

         //// UTC to locale converting

        simpleDateFormatter.setTimeZone(TimeZone.getDefault());
        simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

        Date getDate = simpleDateFormatter.parse(utcDate);
        Date getTime = simpleTimeFormatter.parse(utcTime);

        String getLocalDate = simpleDateFormatter.format(getDate);
        String getLocalTime = simpleTimeFormatter.format(getTime);
        System.out.println("Get local date: " + getLocalDate);
        System.out.println("Get local time: " + getLocalTime);

    } catch (ParseException e) {
        e.printStackTrace();
    }
  }
 }

我送当地的日期和放大器;时间到Web服务，然后要求我需要检索的UTC日期和放大器时;时间，然后转换成语言环境日期和放大器;时间（即用户的本地设置）。

I am sending local date & time to the web service, and then when require I need to retrieve the UTC date & time and then convert into locale date & time (i.e. user's local settings).

示例输出：

Locale:11/9/12 8:15 PM
After parsing a date: Fri Nov 09 20:15:00 SGT 2012
Today's only date: 09/11/2012
Today's only time: 08:15:30 PM
Convert into UTC's date: 09/11/2012
Convert into UTC's only time: 12:15:30 PM
Get local date: 09/11/2012
Get local time: 12:15:30 PM

---

Saksak＆放后; ADTC答案：

对于code片段，UTC日期和放大器;时间（什么是真正的未来的 GMT-5 的数据库，因为可能在美国）是输入的，我希望得到当地日期和放大器;时间作为输出。但是，这下段仍然给的 GMT-5 的时间。

For the code fragment, UTC date & time (what is actually coming as GMT-5 because database may be in USA) is the input, and I want to get local date & time as output. But this following segment is still giving GMT-5 time.

SimpleDateFormat simpleDateTimeFormatter = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a");

....

Date inDateTime = simpleDateTimeFormatter.parse(intent.getExtras().getString("inTime")); Date outDateTime = simpleDateTimeFormatter.parse(intent.getExtras().getString("outTime"));

simpleDateTimeFormatter.setTimeZone(TimeZone.getDefault()); simpleDateTimeFormatter.setTimeZone(simpleDateTimeFormatter.getTimeZone());

//TimeZone tzTimeZone = TimeZone.getDefault();

//System.out.println("Current time zone: " + tzTimeZone.getDisplayName());

String getLocalInTimeString = simpleDateTimeFormatter.format(inDateTime); 

String getLocalOutTimeString = simpleDateTimeFormatter.format(outDateTime);

我的问题： getLocalInTimeString ＆安培; getLocalOutTimeString 仍表现出的 GMT-5 的时机。什么是错在这里？我是否需要设置任何其他的东西？

My question: getLocalInTimeString & getLocalOutTimeString still showing GMT-5 timing. What's wrong here? Do I need to set any other things?

推荐答案

您需要做的，解决你的问题如下，你有你的code转换回本地时间顺序如下：

What you need to do to solve your problem is the following, you have your code to convert back to local time in this order :

simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);

而你需要做的是等待，直到你解析utcDate，utcTime字符串返回Date对象
然后设置日期格式时区到本地区域如下：

and what you need to do is wait until you parse utcDate, utcTime Strings back to Date Object then set the date formatter time zone to local zone as follows :

Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);

simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

这应该打印正确的日期/时间在本地。

this should print the correct date/time in local.

编辑：
这里是完整的主要方法：

here is the full main method :

public static void main(String[] args) {
    DateFormat dateFormatter = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, Locale.getDefault());
    TimeZone.setDefault(TimeZone.getDefault());
    SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("dd/MM/yyyy");
    SimpleDateFormat simpleTimeFormatter = new SimpleDateFormat("hh:mm:ss a");
    Date today = new Date();
    String localeFormattedInTime = dateFormatter.format(today);
    try {
        Date parsedDate = dateFormatter.parse(localeFormattedInTime);
        System.out.println("Locale:" + localeFormattedInTime);
        System.out.println("After parsing a date: " + parsedDate);

        simpleDateFormatter.setTimeZone(TimeZone.getDefault());
        simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

        String date = simpleDateFormatter.format(today);
        String time = simpleTimeFormatter.format(today);
        System.out.println("Today's only date: " + date);
        System.out.println("Today's only time: " + time);

        //// Locale to UTC converting

        System.out.println("TimeZone.getDefault() >>> " + TimeZone.getDefault());

        simpleDateFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
        simpleTimeFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));

        String utcDate = simpleDateFormatter.format(today);
        String utcTime = simpleTimeFormatter.format(today);
        System.out.println("Convert into UTC's date: " + utcDate);
        System.out.println("Convert into UTC's only time: " + utcTime);

        //// UTC to locale converting
        /**
         ** //////EDIT
        */
        // at this point your utcDate,utcTime are strings that are formated in UTC
        // so first you need to parse them back to Dates using UTC format not Locale
        Date getDate = simpleDateFormatter.parse(utcDate);
        Date getTime = simpleTimeFormatter.parse(utcTime);

        // NOW after having the Dates you can change the formatters timezone to your
        // local to format them into strings
        simpleDateFormatter.setTimeZone(TimeZone.getDefault());
        simpleTimeFormatter.setTimeZone(TimeZone.getDefault());

        String getLocalDate = simpleDateFormatter.format(getDate);
        String getLocalTime = simpleTimeFormatter.format(getTime);
        System.out.println("Get local date: " + getLocalDate);
        System.out.println("Get local time: " + getLocalTime);

    } catch (ParseException e) {
        e.printStackTrace();
    }

}

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