PHP设计模式之装饰者模式代码实例

定义：装饰者模式就是不修改原类代码和继承的情况下动态扩展类的功能。传统的编程模式

定义：

装饰者模式就是不修改原类代码和继承的情况下动态扩展类的功能。传统的编程模式都是子类继承父类实现方法重载，使用装饰器模式，只需添加一个新的装饰器对象，更加灵活，避免类数量和层次过多。

角色：

Component（被装饰对象基类） ConcreteComponent（具体被装饰对象） Decorator（装饰者基类） ContreteDecorator（具体的装饰者类）

示例代码：

//被装饰者基类
interface Component
{
 public function operation();
}
 
//装饰者基类
abstract class Decorator implements Component
{
 protected $component;
 
 public function __construct(Component $component)
 {
 $this->component = $component;
 }
 
 public function operation()
 {
 $this->component->operation();
 }
}
 
//具体装饰者类
class ConcreteComponent implements Component
{
 public function operation()
 {
 echo 'do operation'.PHP_EOL;
 }
}
 
//具体装饰类A
class ConcreteDecoratorA extends Decorator {
 public function __construct(Component $component) {
 parent::__construct($component);
 
 }
 
 public function operation() {
 parent::operation();
 $this->addedOperationA(); // 新增加的操作
 }
 
 public function addedOperationA() {
 echo 'Add Operation A '.PHP_EOL;
 }
}
 
//具体装饰类B
class ConcreteDecoratorB extends Decorator {
 public function __construct(Component $component) {
 parent::__construct($component);
 
 }
 
 public function operation() {
 parent::operation();
 $this->addedOperationB();
 }
 
 public function addedOperationB() {
 echo 'Add Operation B '.PHP_EOL;
 }
}
 
 
class Client {
 
 public static function main() {
 /*
 do operation
 Add Operation A
 */
 $decoratorA = new ConcreteDecoratorA(new ConcreteComponent());
 $decoratorA->operation();
 
 
 /*
 do operation
 Add Operation A 
 Add Operation B 
 */
 $decoratorB = new ConcreteDecoratorB($decoratorA);
 $decoratorB->operation();
 }
 
}
 
Client::main();