php获取页面执行时间

<?php

class runtime
{

    
    function __construct() {
    $db_config = array(
    'host' => '127.0.0.1',
    'port' => 3306,
    'user' => 'root',
    'pwd' => 'root',
    'dbname' => 'test'
    );
    $link = mysql_connect($db_config['host'], $db_config['user'], $db_config['pwd']);
    if (!$link) {
        die('Could not connect: ' . mysql_error());
    }
    mysql_query("set names 'utf8'");
    mysql_select_db($db_config['dbname'], $link) or die('Can\'t use foo : ' . mysql_error());
    }
    
    var $StartTime = 0;
    var $StopTime = 0;
    function get_microtime()
    {
    list($usec, $sec) = explode(' ', microtime());
    return ((float)$usec + (float)$sec);
    }
    function start()
    {
    $this->StartTime = $this->get_microtime();
    }
    function stop()
    {
    $this->StopTime = $this->get_microtime();
    }
    function spent()
    {
        $total = ($this->StartTime-$this->StopTime);
        return round($total * 1000, 1);
    }
}


$runtime= new runtime;
$runtime->start();//计时开始//中间放置需要计时的函数或过程
//for($i=1;$i<=1000;$i++)
//{
//  $id="100";
//  $username="xm";
//  //$this->conn = new Mysql($db_config);
//  //$sql="INSERT INTO tb_user(id,name) values('$id','$username')";
//  //mysql_query($sql);
//}
  for ($i=1; $i<=1000;$i++) {  
      $id = '100';   
      $username = 'xm';   
      $sql[] = '('.$id.',"'.$username.'")';  
 } 
 mysql_query('INSERT INTO tb_user(id,name) values '.implode(',',$sql)); 
$runtime->stop();//计时结束
echo "页面执行时间：".$runtime->spent()."毫秒";