获取毫秒时间戳

<?php
abstract class Millisecond {

private $defaultDigit;

public function __construct($_digit = 4)
{
$this->defaultDigit = $_digit;
}

/*
*
* @param $digit 毫秒的位数，0表示不使用毫秒
*/
final function get_time()
{
$counter = $this->defaultDigit;
if(!$counter) return time();

if ($counter != 3) {
$tmp_time = 10;
while(--$counter) {
$tmp_time *= 10;
}
} else {
$tmp_time = 1000;
}

$time = explode (" ", microtime());
$time = $time[1] . ($time[0] * $tmp_time);
$time = explode ( ".", $time );
$time = $time[0];

return $time;
}

/**
* 计算时间位数
* @param  [type] $time [description]
* @return [type]       [description]
*/
final function calcDigit($time)
{
return strlen($time);
}

/**
* 根据指定位数，判断是否可以使用
* @param  [type]  $digit [description]
* @return boolean        [description]
*/
final function isOutput($digit)
{
if(($this->defaultDigit + 10) == $digit) return true;
else return false;
}

/**
* 获取时间戳
* @param  [type] $count [description]
* @return [type]        [description]
*/
abstract function getMillisecond();
}

<?php
require "./time.php";

class MyTime extends Millisecond{

public function __construct($_digit = 5)
{
parent::__construct($_digit);
}

public function getMillisecond(){
$time = $this->get_time();
if ($this->isOutput($this->calcDigit($time))) {
return $time;
} else {
return $this->getMillisecond();
}
}
}

$mytime = new MyTime();

echo $mytime->getMillisecond();