# 装饰器模式（Decorator）

## 概述：

## 模式核心思想：

1. 装饰器模式（Eecorator），可以动态地添加修改类的功能
2. 一个类提供了一项功能，如果要在修改并添加额外的功能，传统的编程模式，需要写一个子类集成它，并重新实现类的方法．
3. 使用装饰器模式，进需在运行时添加一个装饰器对象即可实现，可以实现最大的灵活性

## 模式架构简单代码实现示例：

```php
<?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();
echo '<br>--------<br>';
$decoratorB->operation();
```


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