Java 11 时间 – 是否为今天的时间戳（long）。

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英文:

Java 11 time - is (long)timestamp today

问题

我在一个Mongo文档字段中有一个cron作业字符串。我通过以下方式获得下一个有效的（长时间）时间：

  1. CronExpression exp = new CronExpression(billing.getReminder());
  2. 				
  3. long nextReminder = exp.getNextValidTimeAfter(new Date()).getTime();

我的想法是检查这个“nextReminder”是否是今天，如果是，就创建一些任务。在Java 11中，最好的方法是什么？

英文:

I have a cronjob string saved in a mongo document field. I get the next valid (long)time by

  1. CronExpression exp = new CronExpression(billing.getReminder());
  2. 			
  3. long nextReminder = exp.getNextValidTimeAfter(new Date()).getTime();

My idea is to check if this "nextReminder" isToday() then create some task.
What is the best way to check it with java 11?

答案1

得分: 2

你可以使用 java.time 进行比较...

有一个 Instant 表示一个时间点，就像 epoch 毫秒时间戳一样（表示为你的 long nextReminder），以及 OffsetDateTime.now() 表示实际的当前时刻 now，以及 LocalDate 表示仅包含日期部分。

你可以使用类似下面的方法来判断 nextReminder 是否是今天：

  1. /**
  2.  * <p>
  3.  * 检查给定时间戳（以 epoch 毫秒表示）的日期（或日期部分）
  4.  * 是否与&lt;em&gt;今天&lt;/em&gt;相同（即执行该方法的当天）。&lt;br&gt;
  5.  * <strong>需要偏移量以便进行比较&lt;/strong&gt;
  6.  * </p>
  7.  *
  8.  * @param epochMillis	要检查的以 epoch 毫秒表示的时间戳
  9.  * @param zoneOffset	要用作比较基准的偏移量
  10.  * @return &lt;code&gt;true&lt;/code&gt; 如果参数的日期与今天的日期相等，
  11.  *         否则为 &lt;code&gt;false&lt;/code&gt;
  12.  */
  13. public static boolean isToday(long epochMillis, ZoneOffset zoneOffset) {
  14. 	// 根据给定的偏移量从参数中提取日期部分
  15. 	LocalDate datePassed = Instant.ofEpochMilli(epochMillis)
  16. 								.atOffset(zoneOffset)
  17. 								.toLocalDate();
  18. 	// 然后根据给定的偏移量从 &quot;now&quot; 中提取日期部分
  19. 	LocalDate today = Instant.now()
  20. 								.atOffset(zoneOffset)
  21. 								.toLocalDate();
  22. 	// 然后返回相等性检查的结果
  23. 	return datePassed.equals(today);
  24. }

然后只需像这样调用它：

  1. boolean isNextReminderToday = isToday(nextReminder, ZoneOffset.systemDefault());

这将使用系统的时区偏移。或许，ZoneOffset.UTC 也是一个明智的选择。

英文:

You could use java.time for a comparison...

There is an Instant representing a moment in time like a timestamp in epoch milliseconds does (&rArr; your long nextReminder) as well as OffsetDateTime.now() for the actual moment now and LocalDate as the part describing the date-part only.

You could find out if the nextReminder is today by using a method like this:

  1. /**
  2.  * &lt;p&gt;
  3.  * Checks if the day (or date) of a given timestamp (in epoch milliseconds)
  4.  * is the same as &lt;em&gt;today&lt;/em&gt; (the day this method is executed).&lt;br&gt;
  5.  * &lt;strong&gt;Requires an offset in order to have a common base for comparison&lt;/strong&gt;
  6.  * &lt;/p&gt;
  7.  *
  8.  * @param epochMillis	the timestamp in epoch milliseconds to be checked
  9.  * @param zoneOffset	the offset to be used as base of the comparison
  10.  * @return &lt;code&gt;true&lt;/code&gt; if the dates of the parameter and today are equal,
  11.  *         otherwise &lt;code&gt;false&lt;/code&gt;
  12.  */
  13. public static boolean isToday(long epochMillis, ZoneOffset zoneOffset) {
  14. 	// extract the date part from the parameter with respect to the given offset
  15. 	LocalDate datePassed = Instant.ofEpochMilli(epochMillis)
  16. 								.atOffset(zoneOffset)
  17. 								.toLocalDate();
  18. 	// then extract the date part of &quot;now&quot; with respect to the given offset
  19. 	LocalDate today = Instant.now()
  20. 								.atOffset(zoneOffset)
  21. 								.toLocalDate();
  22. 	// then return the result of an equality check
  23. 	return datePassed.equals(today);
  24. }

and then just call it like

  1. boolean isNextReminderToday = isToday(nextReminder, ZoneOffset.systemDefault());

which would use the time offset of the system. Maybe, ZoneOffset.UTC could be a smart choice, too.

答案2

得分: 2

The answer by deHaar is correct. However, I felt to write this one because in this case, using the Zone ID (instead of Zone Offset) makes the code a bit simpler and also easier to understand.

  1. import java.time.Instant;
  2. import java.time.LocalDate;
  3. import java.time.ZoneId;
  5. public class Main {
  6.     public static void main(String[] args) {
  7.         // A test data
  8.         long nextReminder = 1597754387710L;
  10.         // Your time-zone e.g. Europe/London
  11.         ZoneId zoneId = ZoneId.of("Europe/London");
  13.         // Next reminder date
  14.         Instant instant = Instant.ofEpochMilli(nextReminder);
  15.         LocalDate nextReminderDate = instant.atZone(zoneId).toLocalDate();
  17.         // Today at the time-zone of Europe/London
  18.         LocalDate today = LocalDate.now(zoneId);
  20.         if (today.equals(nextReminderDate)) {
  21.             System.out.println("The next reminder day is today");
  22.         }
  23.     }
  24. }
  26. **Output:**
  28. The next reminder day is today
英文:

The answer by deHaar is correct. However, I felt to write this one because in this case, using the Zone ID (instead of Zone Offset) makes the code a bit simpler and also easier to understand.

  1. import java.time.Instant;
  2. import java.time.LocalDate;
  3. import java.time.ZoneId;
  5. public class Main {
  6. 	public static void main(String[] args) {
  7. 		// A test data
  8. 		long nextReminder = 1597754387710L;
  10. 		// Your time-zone e.g. Europe/London
  11. 		ZoneId zoneId = ZoneId.of(&quot;Europe/London&quot;);
  13. 		// Next reminder date
  14. 		Instant instant = Instant.ofEpochMilli(nextReminder);
  15. 		LocalDate nextReminderDate = instant.atZone(zoneId).toLocalDate();
  17. 		// Today at the time-zone of Europe/London
  18. 		LocalDate today = LocalDate.now(zoneId);
  20. 		if (today.equals(nextReminderDate)) {
  21. 			System.out.println(&quot;The next reminder day is today&quot;);
  22. 		}
  23. 	}
  24. }

Output:

  1. The next reminder day is today

答案3

得分: 1

使用 apache commons 的 DateUtils.isToday(nextReminder)。

使用你自己的方法。

  1. private static final long MILLIS_PER_DAY = 86400000;
  3. public static boolean isToday(long timestamp) {
  4.    long now =  System.currentTimeMillis();
  5.    long today = now.getTime() / MILLIS_PER_DAY;
  6.    long expectedDay = timestamp / MILLIS_PER_DAY;
  7.    return today == expectedDay;
  8. }

注意：在处理日期/时间时考虑使用 UTC。

英文:

Using apache commons DateUtils.isToday(nextReminder)

Using your own method.

  1. private static final long MILLIS_PER_DAY = 86400000;
  3. public static boolean isToday(long timestamp) {
  4.    long now =  System.currentTimeMillis();
  5.    long today = now.getTime() / MILLIS_PER_DAY;
  6.    long expectedDay = timestamp / MILLIS_PER_DAY;
  7.    return today == expectedDay;
  8. }

Note: Consider using UTC when working with date/time.

huangapple
  • 本文由 发表于 2020年8月18日 20:13:23
  • 转载请务必保留本文链接：https://go.coder-hub.com/63468352.html
  • java
  • java-time
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