将对象放到session中形成单列模式

<?php

/*

燕十八 公益PHP培训    课堂地址:YY频道88354001   学习社区:www.zixue.it
	将对象放到SESSION中形成单列模式

*/

                //打开session

                session_start();

	final class CartTool{

		private static $cart = null;

		public static $items = array();

		//保护构造函数,防止new

		final protected function __construct(){

			$this->test = mt_rand(10,48);

		}

		private function __clone(){}

		//判断是否存在了对象

		protected function getIns(){

			if(!self::$cart instanceof self){

				self::$cart = new self;

			}

			return self::$cart;

		}

		//将对象放到session中形成单列模式

		public static function getCart(){

			if(!isset($_SESSION['cart']) || !($_SESSION['cart'] instanceof self)){

				$_SESSION['cart'] = self::getIns();

			}

			return $_SESSION['cart'];

		}