java 在 ZonedDateTime 或 Instant 中将小时分和秒设置为 00
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Set hours minutes and seconds to 00 in ZonedDateTime or Instant
提问by WitVault
I have a date string in Utc format -
我有一个 Utc 格式的日期字符串 -
String dateStr = "2017-03-03T13:14:28.666Z";
And I want to convert it to below format in Java date representation in ZonedDateTime.
我想在ZonedDateTime 中将其转换为 Java 日期表示中的以下格式。
When ZonedDateTimeis printed it should show
当ZonedDateTime打印出来时，它应该显示
String dateStr = "2017-03-03T00:00:00.000Z";
I have tried following code -
我试过以下代码 -
String timeZone = "America/Los_Angeles";
DateTimeFormatter dtf1 = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX");
DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
ZoneId zoneId1 = ZoneId.of(timeZone);
String dateStr = "2017-03-03T13:14:28.666Z";
Instant inst = Instant.parse(dateStr, dtf2);
ZonedDateTime dateTimeInTz = ZonedDateTime.ofInstant(inst, zoneId1);
ZonedDateTime startTime = dateTimeInTz.with(LocalTime.of(0, 0, 0, 0));
ZonedDateTime endTime = dateTimeInTz.with(LocalTime.MAX);
System.out.println("Start:"+startTime+", End:"+endTime);
System.out.println("Start:"+startTime.toString()+", End:"+endTime.toString());
ZonedDateTime nT = ZonedDateTime.of ( LocalDate.parse(dateStr, dtf1) , LocalTime.of (0,0,0,0) , ZoneId.of ( timeZone ) );
System.out.println("Start:"+nT);
Output:
输出：
Start:2017-03-03T00:00-08:00[America/Los_Angeles], End:2017-03-03T23:59:59.999999999-08:00[America/Los_Angeles]
Start:2017-03-03T00:00-08:00[America/Los_Angeles], End:2017-03-03T23:59:59.999999999-08:00[America/Los_Angeles]
Start:2017-03-03T00:00-08:00[America/Los_Angeles]
I want the start time to be normalized in ZonedDateTime. I want to achieve it using java libraries only not any third party library.
我希望在 ZonedDateTime 中标准化开始时间。我只想使用 java 库而不是任何第三方库来实现它。
回答by Basil Bourque
tl;dr
tl;博士
You are working too hard.
你工作太辛苦了。
Instant.parse( "2017-03-03T13:14:28.666Z" )
.truncatedTo( ChronoUnit.DAYS )
.toString()
2017-03-03T00:00.00Z
2017-03-03T00:00.00Z
Details
细节
What does "normalized in ZonedDateTime" mean? Please edit your Question to clarify.
“在 ZonedDateTime 中标准化”是什么意思？请编辑您的问题以澄清。
When ZonedDateTime is printed it should show … "2017-03-03T00:00:00.000Z"
当 ZonedDateTime 打印出来时，它应该显示……“2017-03-03T00:00:00.000Z”
What you are asking is a contradiction. A ZonedDateTimehas an assigned time zone for when you want to view a moment though the wall-clock time of a particular region. So asking for a ZonedDateTimeto generate a string in UTC such as "2017-03-03T00:00:00.000Z"makes no sense. The Zis short for Zuluand means UTC.
你问的是矛盾的。AZonedDateTime具有指定的时区，供您通过特定区域的挂钟时间查看某个时刻。因此，要求 aZonedDateTime以 UTC 格式生成字符串"2017-03-03T00:00:00.000Z"是没有意义的。TheZ是ZuluUTC 的缩写，表示 UTC。
Your input string is in standard ISO 8601 format. The java.time classes use these standard formats by default. So no need to specify a formatting pattern, no need for the DateTimeFormatterclass.
您的输入字符串采用标准 ISO 8601 格式。java.time 类默认使用这些标准格式。所以不需要指定格式模式，不需要DateTimeFormatter类。
Parse as an Instant, a point on the timeline in UTC with a resolution of nanoseconds.
解析为InstantUTC 时间轴上的一个点，分辨率为纳秒。
Instant instant = Instant.parse( "2017-03-03T13:14:28.666Z" );
If you want midnight in UTC, truncate.
如果您想要 UTC 的午夜，请截断。
Instant instantMidnightUtc = instant.truncatedTo( ChronoUnit.DAYS );
instantMidnightUtc.toString(): 2017-03-03T00:00.00Z
InstantMidnightUtc.toString(): 2017-03-03T00:00.00Z
No need for the ZonedDateTimeclass.
不需要ZonedDateTime上课。
If you want to work with a date-only without any time-of-day and without a time zone, use the LocalDateclass.
如果您想使用没有任何时间和时区的仅日期，请使用LocalDate该类。
By the way, do not assume the first moment of the day is always 00:00:00. That is true for UTC. But various time zones may have anomalies such as Daylight Saving Time (DST) where the day may start at another time-of-day such as 01:00:00.
顺便说一句，不要假设一天中的第一个时刻总是00:00:00。这对于 UTC 来说是正确的。但是，不同的时区可能存在异常，例如夏令时 (DST)，其中一天可能从另一个时间开始，例如01:00:00。
About java.time
关于 java.time
The java.timeframework is built into Java 8 and later. These classes supplant the troublesome old legacydate-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
该java.time框架是建立在Java 8和更高版本。这些类取代了麻烦的旧的遗留日期时间类，例如java.util.Date, Calendar, & SimpleDateFormat。
The Joda-Timeproject, now in maintenance mode, advises migration to the java.timeclasses.
现在处于维护模式的Joda-Time项目建议迁移到java.time类。
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
要了解更多信息，请参阅Oracle 教程。并在 Stack Overflow 上搜索许多示例和解释。规范是JSR 310。
Where to obtain the java.time classes?
从哪里获得 java.time 类？
- Java SE 8and SE 9and later
- Built-in.
- Part of the standard Java API with a bundled implementation.
- Java 9 adds some minor features and fixes.
- Java SE 6and SE 7
- Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
- Android
- The ThreeTenABPproject adapts ThreeTen-Backport(mentioned above) for Android specifically.
- See How to use ThreeTenABP….
- Java SE 8和SE 9及更高版本
- 内置。
- 具有捆绑实现的标准 Java API 的一部分。
- Java 9 添加了一些小功能和修复。
- Java SE 6和SE 7
- 多的java.time功能后移植到Java 6和7在ThreeTen-反向移植。
- 安卓
- 所述ThreeTenABP项目适应ThreeTen-反向移植（上述）为Android特异性。
- 请参阅如何使用ThreeTenABP ...。
The ThreeTen-Extraproject extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.
该ThreeTen-额外项目与其他类扩展java.time。该项目是未来可能添加到 java.time 的试验场。你可能在这里找到一些有用的类，比如Interval，YearWeek，YearQuarter，和更多。
回答by hartar
String timeZone = "America/Los_Angeles";
DateTimeFormatter dtf1 = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX");
DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
ZoneId zoneId1 = ZoneId.of(timeZone);
String dateStr = "2017-03-03T13:14:28.666Z";
Instant inst = Instant.parse(dateStr, dtf2);
ZonedDateTime dateTimeInTz = ZonedDateTime.ofInstant(inst, zoneId1);
ZonedDateTime startTime = dateTimeInTz.with(LocalTime.of(0, 0, 0, 0));
ZonedDateTime endTime = dateTimeInTz.with(LocalTime.MAX);
String strStart = (startTime.toString().split("T"))[0] + "T00:00:00.000Z";
String strEnd = (endTime.toString().split("T"))[0] + "T00:00:00.000Z";
System.out.println("Start:"+strStart +", End:"+strEnd );
EDIT new method :
编辑新方法：
TimeZone timeZone = TimeZone.getTimeZone("Europe/Copenhagen");
Calendar cal = Calendar.getInstance(timeZone);
Calendar defaut = new GregorianCalendar( cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH),0,0,0);
You juste need to get all your necessary fields. With, for example, a dateFormat.
您只需要获取所有必需的字段。例如，使用 dateFormat。
Hope it will help you
希望它会帮助你
回答by mir
You can simply do:
你可以简单地做：
DateUtils.truncate(yourDate, Calendar.DAY_OF_MONTH);
Hope this will help you
希望能帮到你
