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<?php/** * php设计模式 单例模式 */class Fruit{private static $instanceMap = array（）;//protected getter for singleton instancesprotected static function getSingleton（$className）{//保证单例模式 并且不能从控制器实例化和克隆if （！isset（self::$instanceMap[$className]）） {$object = new $className;//Make sure this object inherit from Singletonif （$object instanceof Fruit） {self::$instanceMap[$className] = $object;var_dump（$object）;} else {throw SingletonException（"Class "$className" do not inherit from Singleton！"）;}}return self::$instanceMap[$className];}//protected constructor to prevent outside instantiationprotected function __construct（）{}//denie cloning of singleton objectspublic final function __clone（）{trigger_error（"It is impossible to clone singleton", E_USER_ERROR）;}}class Apple extends Fruit{protected $rndId;public function __construct（）{$this->rndId = rand（）;}public function whatAmI（）{echo "I am a Apple（" . $this->rndId . "）<br />";}public static function getInstance（）{//echo get_class（）;return Fruit::getSingleton（get_class（））;}}class GreenApple extends Apple{public function whatAmI（）{echo "I am a GreenApple（" . $this->rndId . "）<br />";}public static function getInstance（）{return Fruit::getSingleton（get_class（））;}}$apple1 = Apple::getInstance（）;//var_dump（$apple1）;$apple2 = GreenApple::getInstance（）;$apple1->whatAmI（）;// should echo "I am a Apple（some number）$apple2->whatAmI（）;// should echo "I am a GreenApple（some number）$apple1 = Apple::getInstance（）;$apple2 = GreenApple::getInstance（）;//保证单例模式$apple1->whatAmI（）;// should echo "I am a Apple（same number as above）$apple2->whatAmI（）;// should echo "I am a GreenApple（same number as above）// $a = clone $apple1;// this should fail// $b = clone $apple2;// this should fail