PHP設計模式之裝飾者模式代碼實例

定義：

裝飾者模式就是不修改原類代碼和繼承的情況下動態擴展類的功能。傳統的編程模式都是子類繼承父類實現方法重載，使用裝飾器模式，只需添加一個新的裝飾器對象，更加靈活，避免類數量和層次過多。

角色：

Component（被裝飾對象基類）
ConcreteComponent（具體被裝飾對象）
Decorator（裝飾者基類）
ContreteDecorator（具體的裝飾者類）

示例代碼：

//被裝飾者基類
interface Component
{
  public function operation();
}
 
//裝飾者基類
abstract class Decorator implements Component
{
  protected $component;
 
  public function __construct(Component $component)
  {
    $this->component = $component;
  }
 
  public function operation()
  {
    $this->component->operation();
  }
}
 
//具體裝飾者類
class ConcreteComponent implements Component
{
  public function operation()
  {
    echo 'do operation'.PHP_EOL;
  }
}
 
//具體裝飾類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;
  }
}
 
//具體裝飾類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();