如何在Java中将时代的秒数转换成小时/分钟/秒？ [英] How can I convert seconds since the epoch to hours/minutes/seconds in Java?

问题描述

有没有一个快速，低垃圾的方法呢？我不能做简单的模数运算，因为这并不代表闰秒和其他日期/时间有趣的事情。

解决方案

这是一个快速，零垃圾的解决方案。每次调用时都不要创建一个 Calendar 的新实例，因为它是一个非常重的对象，占用了448字节的堆，几乎要微秒进行初始化（Java 6 ，64位HotSpot，OS X）。

HmsCalculator 旨在用于单个线程（每个线程必须使用不同的实例）。

  public class HmsCalculator 
 {
 private final Calendar c = Calendar.getInstance（）; 
 
 public Hms toHms（long t）{return toHms（t，new Hms（））; } 
 public Hms toHms（long t，Hms hms）{
 c.setTimeInMillis（t * 1000）; 
 return hms.init（c）; 
} 
 public static class Hms {
 public int h，m，s; 
 private Hms init（Calendar c）{
 h = c.get（HOUR_OF_DAY）; m = c.get（MINUTE）; s = c.get（SECOND）; 
返回这个; 
} 
 public String toString（）{return String.format（％02d：％02d：％02d，h，m，s）; } 
} 
 
 public static void main（String [] args）{
 System.out.println（new HmsCalculator（）。toHms（
 System.currentTimeMillis ）/ 1000））; 
} 
} 
  

我没有粘贴所有这些静态导入（无聊）。

Is there a fast, low-garbage way to do it? I can't just do simple modulus arithmetic since that doesn't account for leap seconds and other date/time funny business.

解决方案

This is a fast, zero-garbage solution. It is of key importance not to create a new instance of Calendar on each call because it's quite a heavyweight object, taking 448 bytes of heap and almost a microsecond to initialize (Java 6, 64-bit HotSpot, OS X).

HmsCalculator is intended for use from a single thread (each thread must use a different instance).

public class HmsCalculator
{
  private final Calendar c = Calendar.getInstance();

  public Hms toHms(long t) { return toHms(t, new Hms()); }
  public Hms toHms(long t, Hms hms) {
    c.setTimeInMillis(t*1000);
    return hms.init(c);
  }
  public static class Hms {
    public int h, m, s;
    private Hms init(Calendar c) {
      h = c.get(HOUR_OF_DAY); m = c.get(MINUTE); s = c.get(SECOND);
      return this;
    }
    public String toString() { return String.format("%02d:%02d:%02d",h,m,s); }
  }

  public static void main(String[] args) {
    System.out.println(new HmsCalculator().toHms(
       System.currentTimeMillis()/1000));
  }
}

P.S. I didn't paste all those static imports (boring).

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