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();