<?php /** * 单例模式 * * 保证一个类仅有一个实例,并提供一个访问它的全局访问点 * */ class Singleton { static private $_instance = null; private function __construct() { } static public function getInstance() { if(is_null(self::$_instance)) { self::$_instance = new Singleton(); } return self::$_instance; } public function display() { echo "it is a singlton class function"; } } // $obj = new Singleton(); // 声明不能成功 $obj = Singleton::getInstance(); var_dump($obj); $obj->display(); $obj1 = Singleton::getInstance(); var_dump(($obj === $obj1));