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();