php设计模式：简单工程模式

<?php
/*
* 子类
*/
class Dog {
public function __construct() {
echo 'dog';
}
}

class Cat {
public function __construct() {
echo 'cat';
}
}

class Duck {
public function __construct() {
echo 'duck';
}
}

/*
* 工厂类
*/
class SimpleFactory {
public static function createAnimal($animalName) {
if (!class_exists($animalName)) {
die("class {$animalName} does not exist!");
}
return new $animalName();
}
}

$dog = SimpleFactory::createAnimal('Dog');
$cat = SimpleFactory::createAnimal('Cat');
$duck = SimpleFactory::createAnimal('Duck');