14 Decorator

动态地给一个对象增加一些额外的职责。就增加功能而言，Decorator模式比生成子类更为灵活。

 

// from: Design Patterns Elements of reusable Object-Oriented Software
using System;

namespace DesignPatterns_Decorator
{
    public abstract class VisualComponent
    {
        public virtual void Draw()
        {
            Console.WriteLine("Draw Visual Component.");
        }
    }

    public class TextView : VisualComponent
    {
        public override void Draw()
        {
            base.Draw();
            Console.WriteLine("Draw TextView");
        }
    }

    public abstract class Decorator : VisualComponent
    {
        public Decorator(VisualComponent v) {
            this.component = v;
        }
        private VisualComponent component;
        public override void Draw()
        {
            component.Draw();
        }
    }

    public class ConcreteDecorator1 : Decorator
    {
        public ConcreteDecorator1(VisualComponent v) : base(v) { }
       
        public override void Draw()
        {
            base.Draw();
            Console.WriteLine("ConcreteDecorator1 draw");
        }
    }

    public class ConcreteDecorator2 : Decorator
    {
        public ConcreteDecorator2(VisualComponent v) : base(v) { }

        public override void Draw()
        {
            base.Draw();
            Console.WriteLine("ConcreteDecorator2 draw");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {

            TextView tv = new TextView();
            Decorator de = new ConcreteDecorator1(tv);
            Decorator de2 = new ConcreteDecorator2(de);
            Decorator de11 = new ConcreteDecorator1(de2);
            //Decorator的递归嵌套
            de11.Draw();
            Console.ReadLine();

        }
    }

}

//////////////以下来自视频教程：

    public abstract class MyClass
    {
        public  abstract void Fun1();
        public  abstract void Fun2();
    }

/////////////////////////////////
    public class Decorator: MyClass
    {
        MyClass _mc = null;
        public Decorator(MyClass mc)
        {
            this._mc = mc;
        }
        public override void Fun1()
        {
            _mc.Fun1();            
        }
        public override void Fun2()
        {
            _mc.Fun2();
        }
    }
//////////////////////////////////
    public class DecoratorA : Decorator
    {
        public DecoratorA(MyClass mc) : base(mc) { }

        public override void Fun1()
        {
            //增加一个功能点
            Console.WriteLine("I can fly.");
            base.Fun1();
        }
        public override void Fun2()
        {
            Console.WriteLine("I can fly too.");
            base.Fun2();
        }
    }
//////////////////////////////////
    public class DecoratorB: Decorator
    {
        public DecoratorB(MyClass mc) : base(mc) { }


        public override void Fun1()
        {
            Console.WriteLine("i can run");
            base.Fun1();
        }

        public override void Fun2()
        {
            Console.WriteLine("i can run too");
            base.Fun2();
        }

    }

//////////////////////////////////

    public class DecoratorC: Decorator
    {

        public DecoratorC(MyClass mc) : base(mc) { }


        public override void Fun1()
        {
            Console.WriteLine("i can swim");
            base.Fun1();
        }

        public override void Fun2()
        {
            Console.WriteLine("i can swim too");
            base.Fun2();
        }

    }
//////////////////////////////////
    public class MyClassConcrete: MyClass
    {
        public override void Fun1()
        {
            Console.WriteLine(this.GetType().ToString() +" : Fun1");
        }

        public override void Fun2()
        {
            Console.WriteLine(this.GetType().ToString()+" : Fun2");
        }
    }
//////////////////////////////////
 static void Main(string[] args)
        {
            MyClass mc = new Decorator(new MyClassConcrete());

            mc.Fun1();
            mc.Fun2();

            DecoratorA da = new DecoratorA(mc);
            da.Fun1();
            da.Fun2();

            DecoratorB db = new DecoratorB(da);
            db.Fun1();
            db.Fun2();

            DecoratorC dc = new DecoratorC(db);
            dc.Fun1();
            dc.Fun2();
}