PHP面向对象-单列模式
单例模式,在PHP面向对象中应用的比较广泛, 通常为了节省资源,在性能方面上,代码重用性上考虑,使用设计模式是很不错的选择, 比如数据库操作类系统类库等,通常开源代码都会使用单列模式去设计完成,使用单列模式的优点很明显, 可以保证每个类生成实体的唯一性,性能方面有所提高.
<?phpheader ("Content-Type:text/html; charset=utf8");/** * php设计模式 * 三:单列模式 * */class Sigle{ protected static $instanc = null; protected function __construct(){ } public static function getInstan(){ if(self::$instanc === null){ self::$instanc = new self; } return self::$instanc; } private function __clone(){ echo 'conle'; }}$obj1 = Sigle::getInst();$obj2 = Sigle::getInst();if($obj1 === $obj2){ echo '是一个对象';}else{ echo '不是一个对象';}
解释: 从列子中可以看出, 把构造函数__construct,__clone私有化, 目的是防止new和克隆一个新的对象, 然后开放getInstace这个公共的操作,让其调用保证这个对象的唯一性.

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