我们通常可以用 long ms=System.currentTimeMillis(); 来取得以毫秒为单位起始时间和终止时间，它们的时间差除以一千就知道一段Java程序运行了多少秒，但多少秒并不直观，比如900秒你要反应一下，说15分就马上反应过来了。下面提供了计算的函数 和使用示例代码：
public static void main(String[] args) {
long startMs=System.currentTimeMillis();
... // do something
long endMs=System.currentTimeMillis();
System.out.println("Time elapsed:"+ms2DHMS(startMs,endMs));
}
/**
* change seconds to DayHourMinuteSecond format
*
* @param startMs
* @param endMs
* @return
*/
private static String ms2DHMS(long startMs, long endMs) {
String retval = null;
long secondCount = (endMs - startMs) / 1000;
String ms = (endMs - startMs) % 1000 + "ms";
long days = secondCount / (60 * 60 * 24);
long hours = (secondCount % (60 * 60 * 24)) / (60 * 60);
long minutes = (secondCount % (60 * 60)) / 60;
long seconds = secondCount % 60;
if (days > 0) {
retval = days + "d" + hours + "h" + minutes + "m" + seconds + "s";
} else if (hours > 0) {
retval = hours + "h" + minutes + "m" + seconds + "s";
} else if (minutes > 0) {
retval = minutes + "m" + seconds + "s";
} else if(seconds > 0) {
retval = seconds + "s";
}else {
return ms;
}
return retval + ms;
}
输出示例：
Time elapsed:3m55s872ms
--2020年2月29日--