php设计模式——装饰器模式

装饰器模式，对已有对象的部分内容或者功能进行调整，但是不需要修改原始对象结构，可以使用装饰器

场景事例：

咖啡 1 元一杯，加点牛奶0.2元，加点糖0.2元，在不修改咖啡类的情况下，使用装饰器模式

<?phpabstract class Beverage{public $_name;abstract public function Cost();}// 被装饰者类class Coffee extends Beverage{public function __construct(){$this->_name = 'Coffee';}public function Cost(){return 1.00;}}// 以下两个类是装饰者相关类class Milk extends Coffee{public $_beverage;public function __construct($beverage){$this->_name = 'Milk';$this->_beverage = $beverage;}public function Cost(){return $this->_beverage->Cost() + 0.2;}}class Sugar extends Coffee{public $_beverage;public function __construct($beverage){$this->_name = 'Sugar';$this->_beverage = $beverage;}public function Cost(){return $this->_beverage->Cost() + 0.2;}}// Test Case//1.拿杯咖啡$coffee = new Coffee();//2.加点牛奶$coffee = new Milk($coffee);  //此时的$coffee已经是milk的对象了//3.加点糖$coffee = new Sugar($coffee); //此时的$coffee是糖的对象printf("Coffee Total:%0.2f\n",$coffee->Cost());