设计模式php篇（一）————单例模式

话不多说，直接上代码：

<?php

namespace DesignPattern;

/**
* php设计模式之单例模式
*/
class SingleInstance
{

private static $instance = null;

private function __construct(){}

public static function getInstance()
    {
if(is_null(self::$instance)){
self::$instance = new self();
return self::$instance;
        }
else{
return self::$instance;
        }
    }

}

$instance1 = SingleInstance::getInstance();
var_dump($instance1);
$instance2 = SingleInstance::getInstance();
var_dump($instance2);


/**
打印值为：
/Users/icarus/Code/php/SingleInstance.php:29:
class DesignPattern\SingleInstance#1 (0) {
}
/Users/icarus/Code/php/SingleInstance.php:31:
class DesignPattern\SingleInstance#1 (0) {
}
*/