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装饰器设计模式
装饰器模式就是对一个已有的结构增加装饰。装饰模式是在不必改变原类文件和使用继承的情况下,动态地扩展一个对象的功能。它是通过创建一个包装对象,也就是装饰来包裹真实的对象。
基本说来, 如果想为现有对象增加新功能而不想影响其他对象, 就可以使用装饰器模式.
<?php namespace Test;abstract class Component{ abstract public function operation(); }
<?phpnamespace Test;abstract class Decorator extends Component{ protected $component; public function __construct(Component $component) { $this->component = $component; } public function operation() { $this->component->operation(); } abstract public function before(); abstract public function after();}
<?phpnamespace Test;class ConcreteComponent extends Component{ public function operation() { echo "hello world!!!!"; }}
<?phpnamespace Test;class ConcreteDecoratorA extends Decorator{ public function __construct(Component $component) { parent::__construct($component); } public function operation() { $this->before(); parent::operation(); $this->after(); } public function before() { // TODO: Implement before() method. echo "before!!!"; } public function after() { // TODO: Implement after() method. echo "after!!!"; }}
<?phpnamespace Test;class Client{ /** * */ public static function main() { $decoratorA = new ConcreteDecoratorA(new ConcreteComponent()); $decoratorA->operation(); $decoratorB=new ConcreteDecoratorA($decoratorA); $decoratorB->operation(); }}
before!!!hello world!!!!after!!!before!!!before!!!hello world!!!!after!!!after!!!