如何在不同编程语言中获取现在的Unix时间戳(Unix timestamp)

小鱼儿 2022-01-31 19:37 235阅读 0赞

# 什么是时间戳？ #

Unix时间戳(Unix timestamp)，或称Unix时间(Unix time)、POSIX时间(POSIX time)，是一种时间表示方式，定义为从格林威治时间1970年01月01日00时00分00秒起至现在的总秒数。Unix时间戳不仅被使用在Unix系统、类Unix系统中，也在许多其他操作系统中被广泛采用。多数Unix系统将时间戳以一个32位整型进行保存，这可能会在2038年1月19日产生一些问题（Y2038问题）。

### 如何在不同编程语言中 获取现在的Unix时间戳(Unix timestamp)？ ###

<table> 
 <tbody> 
 <tr> 
 <td>Java</td> 
 <td>time</td> 
 </tr> 
 <tr> 
 <td>JavaScript</td> 
 <td>Math.round(new Date().getTime()/1000) getTime()返回数值的单位是毫秒</td> 
 </tr> 
 <tr> 
 <td>Microsoft .NET / C#</td> 
 <td>epoch = (DateTime.Now.ToUniversalTime().Ticks - 621355968000000000) / 10000000</td> 
 </tr> 
 <tr> 
 <td>MySQL</td> 
 <td>SELECT unix_timestamp(now())</td> 
 </tr> 
 <tr> 
 <td>Perl</td> 
 <td>time</td> 
 </tr> 
 <tr> 
 <td>PHP</td> 
 <td>time()</td> 
 </tr> 
 <tr> 
 <td>PostgreSQL</td> 
 <td>SELECT extract(epoch FROM now())</td> 
 </tr> 
 <tr> 
 <td>Python</td> 
 <td>先&nbsp;import time&nbsp;然后&nbsp;time.time()</td> 
 </tr> 
 <tr> 
 <td>Ruby</td> 
 <td>获取Unix时间戳：Time.now&nbsp;或&nbsp;Time.new 显示Unix时间戳：Time.now.to_i</td> 
 </tr> 
 <tr> 
 <td>SQL Server</td> 
 <td>SELECT DATEDIFF(s, '1970-01-01 00:00:00', GETUTCDATE())</td> 
 </tr> 
 <tr> 
 <td>Unix / Linux</td> 
 <td>date +%s</td> 
 </tr> 
 <tr> 
 <td>VBScript / ASP</td> 
 <td>DateDiff("s", "01/01/1970 00:00:00", Now())</td> 
 </tr> 
 <tr> 
 <td>其他操作系统 (如果Perl被安装在系统中)</td> 
 <td>命令行状态：perl -e "print time"</td> 
 </tr> 
 </tbody> 
</table>

### 如何在不同编程语言中 实现Unix时间戳(*Unix timestamp*) → 普通时间？ ###

<table> 
 <tbody> 
 <tr> 
 <td>Java</td> 
 <td>String date = new java.text.SimpleDateFormat("dd/MM/yyyy HH:mm:ss").format(new java.util.Date(Unix timestamp&nbsp;* 1000))</td> 
 </tr> 
 <tr> 
 <td>JavaScript</td> 
 <td>先&nbsp;var unixTimestamp = new Date(Unix timestamp&nbsp;* 1000)&nbsp;然后&nbsp;commonTime = unixTimestamp.toLocaleString()</td> 
 </tr> 
 <tr> 
 <td>Linux</td> 
 <td>date -d @Unix timestamp</td> 
 </tr> 
 <tr> 
 <td>MySQL</td> 
 <td>from_unixtime(Unix timestamp)</td> 
 </tr> 
 <tr> 
 <td>Perl</td> 
 <td>先&nbsp;my $time =&nbsp;Unix timestamp&nbsp;然后&nbsp;my ($sec, $min, $hour, $day, $month, $year) = (localtime($time))[0,1,2,3,4,5,6]</td> 
 </tr> 
 <tr> 
 <td>PHP</td> 
 <td>date('r',&nbsp;Unix timestamp)</td> 
 </tr> 
 <tr> 
 <td>PostgreSQL</td> 
 <td>SELECT TIMESTAMP WITH TIME ZONE 'epoch' +&nbsp;Unix timestamp) * INTERVAL '1 second';</td> 
 </tr> 
 <tr> 
 <td>Python</td> 
 <td>先&nbsp;import time&nbsp;然后&nbsp;time.gmtime(Unix timestamp)</td> 
 </tr> 
 <tr> 
 <td>Ruby</td> 
 <td>Time.at(Unix timestamp)</td> 
 </tr> 
 <tr> 
 <td>SQL Server</td> 
 <td>DATEADD(s,&nbsp;Unix timestamp, '1970-01-01 00:00:00')</td> 
 </tr> 
 <tr> 
 <td>VBScript / ASP</td> 
 <td>DateAdd("s",&nbsp;Unix timestamp, "01/01/1970 00:00:00")</td> 
 </tr> 
 <tr> 
 <td>其他操作系统 (如果Perl被安装在系统中)</td> 
 <td>命令行状态：perl -e "print scalar(localtime(Unix timestamp))"</td> 
 </tr> 
 </tbody> 
</table>

### 如何在不同编程语言中 实现普通时间 → Unix时间戳(*Unix timestamp*)？ ###

<table> 
 <tbody> 
 <tr> 
 <td>Java</td> 
 <td>long epoch = new java.text.SimpleDateFormat("dd/MM/yyyy HH:mm:ss").parse("01/01/1970 01:00:00");</td> 
 </tr> 
 <tr> 
 <td>JavaScript</td> 
 <td>var commonTime = new Date(Date.UTC(year,&nbsp;month&nbsp;- 1,&nbsp;day,&nbsp;hour,&nbsp;minute,&nbsp;second))</td> 
 </tr> 
 <tr> 
 <td>MySQL</td> 
 <td>SELECT unix_timestamp(time) 时间格式: YYYY-MM-DD HH:MM:SS 或 YYMMDD 或 YYYYMMDD</td> 
 </tr> 
 <tr> 
 <td>Perl</td> 
 <td>先&nbsp;use Time::Local&nbsp;然后&nbsp;my $time = timelocal($sec, $min, $hour, $day, $month, $year);</td> 
 </tr> 
 <tr> 
 <td>PHP</td> 
 <td>mktime(hour,&nbsp;minute,&nbsp;second,&nbsp;month,&nbsp;day,&nbsp;year)</td> 
 </tr> 
 <tr> 
 <td>PostgreSQL</td> 
 <td>SELECT extract(epoch FROM date('YYYY-MM-DD HH:MM:SS'));</td> 
 </tr> 
 <tr> 
 <td>Python</td> 
 <td>先&nbsp;import time&nbsp;然后&nbsp;int(time.mktime(time.strptime('YYYY-MM-DD HH:MM:SS', '%Y-%m-%d %H:%M:%S')))</td> 
 </tr> 
 <tr> 
 <td>Ruby</td> 
 <td>Time.local(year,&nbsp;month,&nbsp;day,&nbsp;hour,&nbsp;minute,&nbsp;second)</td> 
 </tr> 
 <tr> 
 <td>SQL Server</td> 
 <td>SELECT DATEDIFF(s, '1970-01-01 00:00:00',&nbsp;time)</td> 
 </tr> 
 <tr> 
 <td>Unix / Linux</td> 
 <td>date +%s -d"Jan 1, 1970 00:00:01"</td> 
 </tr> 
 <tr> 
 <td>VBScript / ASP</td> 
 <td>DateDiff("s", "01/01/1970 00:00:00",&nbsp;time)</td> 
 </tr> 
 </tbody> 
</table>