<?php class Foo { static private $instances = []; /** * 禁止 new */ protected function __construct() {} /** * 禁止 clone */ final private function __clone() {} final static public function getInstance() { $class = get_called_class(); if (!isset(self::$instances[$class])) { self::$instances[$class] = new static; } return self::$instances[$class]; } } class Bar extends Foo { } $foo = Foo::getInstance(); $bar = Bar::getInstance();