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Aclass 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Bclass 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();