到 Java 日期对象的 Unix 纪元时间

我有一个包含 UNIX 时代的字符串，需要将其转换为 JavaDate 对象。

String date = "1081157732";
DateFormat df = new SimpleDateFormat(""); // This line
try {
Date expiry = df.parse(date);
} catch (ParseException ex) {
ex.getStackTrace();
}

标记线是我遇到麻烦的地方。我不知道 SimpleDateFormat ()的参数应该是什么，甚至不知道我是否应该使用 SimpleDateFormat ()。

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long timestamp = Long.parseLong(date)
Date expiry = new Date(timestamp * 1000)
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最佳答案

How about just:

Date expiry = new Date(Long.parseLong(date));

EDIT: as per rde6173's answer and taking a closer look at the input specified in the question , "1081157732" appears to be a seconds-based epoch value so you'd want to multiply the long from parseLong() by 1000 to convert to milliseconds, which is what Java's Date constructor uses, so:

Date expiry = new Date(Long.parseLong(date) * 1000);
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Hum.... if I am not mistaken, the UNIX Epoch time is actually the same thing as 

System.currentTimeMillis()

So writing

try {
Date expiry = new Date(Long.parseLong(date));
}
catch(NumberFormatException e) {
// ...
}

should work (and be much faster that date parsing)

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Epoch is the number of seconds since Jan 1, 1970..

So:

String epochString = "1081157732";
long epoch = Long.parseLong( epochString );
Date expiry = new Date( epoch * 1000 );

For more information: http://www.epochconverter.com/

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Better yet, use JodaTime. Much easier to parse strings and into strings. Is thread safe as well. Worth the time it will take you to implement it.

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To convert seconds time stamp to millisecond time stamp. You could use the TimeUnit API and neat like this.

long milliSecondTimeStamp = MILLISECONDS.convert(secondsTimeStamp, SECONDS)

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java.time

Using the java.time framework built into Java 8 and later.

import java.time.LocalDateTime;
import java.time.Instant;
import java.time.ZoneId;


long epoch = Long.parseLong("1081157732");
Instant instant = Instant.ofEpochSecond(epoch);
ZonedDateTime.ofInstant(instant, ZoneOffset.UTC); # ZonedDateTime = 2004-04-05T09:35:32Z[UTC]

In this case you should better use ZonedDateTime to mark it as date in UTC time zone because Epoch is defined in UTC in Unix time used by Java.

ZoneOffset contains a handy constant for the UTC time zone, as seen in last line above. Its superclass, ZoneId can be used to adjust into other time zones.

ZoneId zoneId = ZoneId.of( "America/Montreal" );

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