将Java日期转换为UTC字符串 [英] Convert Java Date to UTC String
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问题描述
java.util.Date toString（）方法在本地时区显示日期。
The java.util.Date toString() method displays the date in the local time zone.
有几种常见的情况，我们希望在 UTC ，包括日志，数据导出和与外部程序的通信。
There are several common scenarios where we want the data to be printed in UTC, including logs, data export and communication with external programs.
- 最好的方法是创建一个如何将juDate的
toString（）替换为java.util.Date在UTC中的字符串表示法
< 格式，这是不可排序的（谢谢，@JonSkeet！）更好的格式？
- What's the best way to create a String representation of
java.util.Datein UTC? - How to replace the j.u.Date’s
toString()format, which isn't sortable (thanks, @JonSkeet!) with a better format?
我认为以自定义格式和时区打印日期的标准方式是相当乏味的：
I think that the standard way of printing the date in a custom format and time zone is quite tedious:
final Date date = new Date();
final String ISO_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS zzz";
final SimpleDateFormat sdf = new SimpleDateFormat(ISO_FORMAT);
final TimeZone utc = TimeZone.getTimeZone("UTC");
sdf.setTimeZone(utc);
System.out.println(sdf.format(date));
我正在寻找一个单行，如：
I was looking for a one-liner like:
System.out.println(prettyPrint(date, "yyyy-MM-dd'T'HH:mm:ss.SSS zzz", "UTC"));
推荐答案
根据有用的意见，我已经完全重建日期格式化程序用法应该是：
Following the useful comments, I've completely rebuilt the date formatter. Usage is supposed to:
- 短（一个班轮）
- 代表一次性物品（时区，格式）作为字符串
- 支持有用的，可排序的ISO格式和从框中的旧格式
如果您认为此代码有用，我可能会在github中发布源代码和JAR。
If you consider this code useful, I may publish the source and a JAR in github.
// The problem - not UTC
Date.toString()
"Tue Jul 03 14:54:24 IDT 2012"
// ISO format, now
PrettyDate.now()
"2012-07-03T11:54:24.256 UTC"
// ISO format, specific date
PrettyDate.toString(new Date())
"2012-07-03T11:54:24.256 UTC"
// Legacy format, specific date
PrettyDate.toLegacyString(new Date())
"Tue Jul 03 11:54:24 UTC 2012"
// ISO, specific date and time zone
PrettyDate.toString(moonLandingDate, "yyyy-MM-dd hh:mm:ss zzz", "CST")
"1969-07-20 03:17:40 CDT"
// Specific format and date
PrettyDate.toString(moonLandingDate, "yyyy-MM-dd")
"1969-07-20"
// ISO, specific date
PrettyDate.toString(moonLandingDate)
"1969-07-20T20:17:40.234 UTC"
// Legacy, specific date
PrettyDate.toLegacyString(moonLandingDate)
"Wed Jul 20 08:17:40 UTC 1969"
代码
（此代码也是代码审查stackexchange的问题）
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
/**
* Formats dates to sortable UTC strings in compliance with ISO-8601.
*
* @author Adam Matan <adam@matan.name>
* @see http://stackoverflow.com/questions/11294307/convert-java-date-to-utc-string/11294308
*/
public class PrettyDate {
public static String ISO_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS zzz";
public static String LEGACY_FORMAT = "EEE MMM dd hh:mm:ss zzz yyyy";
private static final TimeZone utc = TimeZone.getTimeZone("UTC");
private static final SimpleDateFormat legacyFormatter = new SimpleDateFormat(LEGACY_FORMAT);
private static final SimpleDateFormat isoFormatter = new SimpleDateFormat(ISO_FORMAT);
static {
legacyFormatter.setTimeZone(utc);
isoFormatter.setTimeZone(utc);
}
/**
* Formats the current time in a sortable ISO-8601 UTC format.
*
* @return Current time in ISO-8601 format, e.g. :
* "2012-07-03T07:59:09.206 UTC"
*/
public static String now() {
return PrettyDate.toString(new Date());
}
/**
* Formats a given date in a sortable ISO-8601 UTC format.
*
* <pre>
* <code>
* final Calendar moonLandingCalendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
* moonLandingCalendar.set(1969, 7, 20, 20, 18, 0);
* final Date moonLandingDate = moonLandingCalendar.getTime();
* System.out.println("UTCDate.toString moon: " + PrettyDate.toString(moonLandingDate));
* >>> UTCDate.toString moon: 1969-08-20T20:18:00.209 UTC
* </code>
* </pre>
*
* @param date
* Valid Date object.
* @return The given date in ISO-8601 format.
*
*/
public static String toString(final Date date) {
return isoFormatter.format(date);
}
/**
* Formats a given date in the standard Java Date.toString(), using UTC
* instead of locale time zone.
*
* <pre>
* <code>
* System.out.println(UTCDate.toLegacyString(new Date()));
* >>> "Tue Jul 03 07:33:57 UTC 2012"
* </code>
* </pre>
*
* @param date
* Valid Date object.
* @return The given date in Legacy Date.toString() format, e.g.
* "Tue Jul 03 09:34:17 IDT 2012"
*/
public static String toLegacyString(final Date date) {
return legacyFormatter.format(date);
}
/**
* Formats a date in any given format at UTC.
*
* <pre>
* <code>
* final Calendar moonLandingCalendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
* moonLandingCalendar.set(1969, 7, 20, 20, 17, 40);
* final Date moonLandingDate = moonLandingCalendar.getTime();
* PrettyDate.toString(moonLandingDate, "yyyy-MM-dd")
* >>> "1969-08-20"
* </code>
* </pre>
*
*
* @param date
* Valid Date object.
* @param format
* String representation of the format, e.g. "yyyy-MM-dd"
* @return The given date formatted in the given format.
*/
public static String toString(final Date date, final String format) {
return toString(date, format, "UTC");
}
/**
* Formats a date at any given format String, at any given Timezone String.
*
*
* @param date
* Valid Date object
* @param format
* String representation of the format, e.g. "yyyy-MM-dd HH:mm"
* @param timezone
* String representation of the time zone, e.g. "CST"
* @return The formatted date in the given time zone.
*/
public static String toString(final Date date, final String format, final String timezone) {
final TimeZone tz = TimeZone.getTimeZone(timezone);
final SimpleDateFormat formatter = new SimpleDateFormat(format);
formatter.setTimeZone(tz);
return formatter.format(date);
}
}
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