PHP学习：单例

<?php header('Content-type :text/html ; charset = utf-8');class Person{private $hash;static private $p;private function __construct(){$this->hash = mt_rand(1,99999);}static public function getInstance(){if(self::$p instanceof self){return self::$p;}self::$p = new self();return self::$p;}}$p1 = Person::getInstance();print_r($p1);echo '<br/>';$p2 = Person::getInstance();print_r($p2);echo '<br/>';$p3 = Person::getInstance();print_r($p3);echo '<br/>';?>