将日期时间字符串转换为Unix时间戳

Question

I have a string for date time coming as like this without any spaces in between them:

TueDec2618:47:09UTC2017

Is there any way to convert this to unix timestamps? The date time string will always be in that format.

Answer 1

java.time and ThreeTen Backport

The comment by ernest_k is well thought out and solves your issue:

    DateTimeFormatter formatter
            = DateTimeFormatter.ofPattern("EEEMMMddHH:mm:sszyyyy", Locale.ENGLISH);
    String dateTimeString = "TueDec2618:47:09UTC2017";
    ZonedDateTime dateTime = ZonedDateTime.parse(dateTimeString, formatter);
    long unixTimestamp = dateTime.toEpochSecond();
    System.out.println("Parsed date-time " + dateTime + " Unix timestamp " + unixTimestamp);

The output from running on ThreeTen Backport 1.3.6, tested on Java 1.7.0_79, is:

Parsed date-time 2017-12-26T18:47:09Z[Zulu] Unix timestamp 1514314029

Question: How can I use ZonedDateTime and DateTimeFormatter on Java 7?

I am still on Java 7 btw so can't use ZonedDataTime and DateTimeFormatter but I can use joda library.

Indeed you can. java.time just requires at least Java 6 .

• In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
• In Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
• On (older) Android use the Android edition of ThreeTen Backport. It's called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

While Joda-Time would be another nice solution, I believe that you should prefer the ThreeTen Backport over Joda-Time (though opinions differ). The Joda-Time home page advises:

Note that Joda-Time is considered to be a largely “finished” project. No major enhancements are planned. If using Java SE 8, please migrate to java.time (JSR-310).

So java.time seems to be the future-proof solution.

Links

• Oracle tutorial: Date Time explaining how to use java.time.
• Java Specification Request (JSR) 310 , where java.time was first described.
• ThreeTen Backport project , the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
• ThreeTenABP , Android edition of ThreeTen Backport
• Question: How to use ThreeTenABP in Android Project , with a very thorough explanation.
• Joda-Time home page