PHP设计模式 - 装饰器模式

<?php
interface Component {
    public function operation();
}

abstract class Decorator implements Component{ // 装饰角色 
    protected  $_component;
    public function __construct(Component $component) {
        $this->_component = $component;
    }
    public function operation() {
        $this->_component->operation();
    }
}

class ConcreteDecoratorA extends Decorator { // 具体装饰类A
    public function __construct(Component $component) {
        parent::__construct($component);
    } 
    public function operation() {
        parent::operation();    //  调用装饰类的操作
        $this->addedOperationA();   //  新增加的操作
    }
    public function addedOperationA() {echo ‘A加点酱油;‘;}
}

class ConcreteDecoratorB extends Decorator { // 具体装饰类B
    public function __construct(Component $component) {
        parent::__construct($component);
    } 
    public function operation() {
        parent::operation();
        $this->addedOperationB();
    }
    public function addedOperationB() {echo "B加点辣椒;";}
}

class ConcreteComponent implements Component{ //具体组件类
    public function operation() {} 
}

// clients
$component = new ConcreteComponent();
$decoratorA = new ConcreteDecoratorA($component);
$decoratorB = new ConcreteDecoratorB($decoratorA);

$decoratorA->operation();//输出：A加点酱油;
echo ‘<br>--------<br>‘;
$decoratorB->operation();//输出：A加点酱油;B加点辣椒;
?>