由于我以前是做java开发的,在使用单例模式的时候,首先想到的想用饿汉式,然后发现在PHP中,有这样一个特性:因为PHP不支持在类定义时给类的成员变量赋予非基本类型的值。如表达式,new操作等等。转而想要确保这个单例模式的原子性,发现PHP中也没有像JAVA中的线程安全问题。
嘿嘿,你说PHP好不好?那么OK接下来就试试PHP的懒汉式单例模式了。
相关推荐:《PHP教程》
一、三私一公:
①、私有静态属性,又来储存生成的唯一对象
②、私有构造函数
③、私有克隆函数,防止克隆——clone
④、公共静态方法,用来访问静态属性储存的对象,如果没有对象,则生成此单例
二、关键词instanceof
检查此变量是否为该类的对象、子类、或是实现接口。
1、一个private的__construct是必须的,单例类不能在其它类中实例化,只能被自身实例化;
2、拥有一个保存类的实例的静态成员变量;
3、一个静态的公共方法用于实例化这个类,并访问这个类的实例;
class SingleInstance{ private function _construct(){ } private static $instance; private function _clone(){ } public static function getInstance(){ if(!self::$instance instanceof SingleInstance){ self::$instance=new SingleInstance(); } return self ::$instance; } }
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