结构

装饰器模式

说明

Attach additional responsibilities to an object dynamically keeping the same interface. Decorators provide a flexible alternative to subclassing for extending functionality.

向某个对象动态地添加更多的功能。修饰模式是除类继承外另一种扩展功能的方法。

适用条件

  • 在不影响其他对象的情况下, 以动态且透明的方式添加单个对象的功能;
  • 处理那些可以撤销的功能;
  • 不能采用生成子类的方法扩充时;

实现

interface IWindow {

   void Draw();

   string GetDescription();

}

class SimpleWindow : IWindow {
   
   public void Draw() {
      //
   }

   public string GetDescription() {
      return "Simple window";
   }
}

class WindowDecorator : IWindow {
   
   protected IWindow DecoratedWindow;

   public WindowDecorator(IWindow decoratedWindow) {
      this.DecoratedWindow = decoratedWindow;
   }

   public virtual void Draw() {
      this.DecoratedWindow.Draw();
   }

   public virtual string GetDescription() {
      return "Window decorator";
   }

}

class VerticalScrollbarWindow : WindowDecorator {

   public VerticalScrollbarWindow(IWindow decoratedWindow) : base(    decoratedWindow) {
   }

   public override void Draw() {
      base.Draw();
      this.DrawVerticalScrollbar();
   }

   private void DrawVerticalScrollbar() {
      //
   }

   public override string GetDescription() {
      return this.DecoratedWindow.GetDescription() + ", include vertical     scrollbars";
   }

}

class HorizontalScrollbarWindow : WindowDecorator {

   public HorizontalScrollbarWindow(IWindow decoratedWindow) : base(    decoratedWindow) {
   }

   public override void Draw() {
      base.Draw();
      this.DrawHorizontalScrollbar();
   }

   private void DrawHorizontalScrollbar() {
      //
   }

   public override string GetDescription() {
      return this.DecoratedWindow.GetDescription() + ", include horizontal     scrollbars";
   }

}

class Program {
   
   static void Main(string[] args) {
      IWindow window = new HorizontalScrollbarWindow(new VerticalScrollbarWindow    (new SimpleWindow()));
      Console.WriteLine(window.GetDescription());

      Console.ReadKey();
   }
}