设计模式-装饰模式

装饰模式基本实现

Component类

abstract class Component
{public abstract void Operation();
}

ConcreteComponent类

class ConcreteComponent:Component{public override void Operation(){Console.WriteLine("具体对象的操作")}
}

Decorator类

abstract class Decorator:Component
{protected Component component;public void SetComponent(Component component){this.component = component;}public override void Operation(){if(component != null){component.Operation();}}    
}

ConcreteDecorator相关类

class ConcreteDecoratorA:Decrator
{private string addedState;public override void Operation(){base.Operation();addedState = "New State";Console.WriteLine("具体装饰对象A的操作")；}
}class ConcreteDecoratorB:Decrator
{private string addedState;public override void Operation(){base.Operation();AddedBehavior();Console.WriteLine("具体装饰对象B的操作")；}public void AddedBehavior(){}
}

客户端代码

static void Main(string[] args){ConcreteComponent c = new ConcreteComponent();ConcreteDecoratorA d1 = new ConcreteDecoratorA();ConcreteDecoratorB d2 = new ConcreteDecoratorB();d1.SetComponent(c);d2.SetComponent(d1);d2.Operation();
}

装饰模式实现换装程序

“Person”类 (ConcreteComponent)

class Person{public Person(){}private string name;public Person(string name){this.name = name;}public virtual void show(){Console.WriteLine("装扮的{0}",name);}
}

服饰类(Decorator)

class Finery:Person
{protected Person component;//打扮public void Decorate(Person component){this.component = component;}public override void Show(){if(component != null){component.Show();}}
}

具体服饰类(ConcreteDecorator)

class TShirts:Finery
{public override void Show(){Console.Write("大T恤");base.show();//调用父类的方法            }
}class BigTrouser:Finery
{public override void Show(){Console.Write("垮裤");base.show();//调用父类的方法            }
}
// ...

客户端代码

static void Main(string[] args){Person xc = new Person("小菜")；Console.WriteLine("\n 第一种装扮：");Sneakers pqx = new Sneakers();BigTrouser kk =new BigTrouser();TShirts dtx = new TShirts();pqx.Decorate(xc);kk.Decorate(pqx);dtx.Decorate(kk);dtx.show();
}

总结

装饰模式是为已有功能动态地添加更多功能地一种方式。

使用场景：当系统需要新功能的时候，是向旧的类中添加新的代码。这些新加的代码通常装饰了原有类的核心职责或主要行为。

优点：把类中的装饰功能从类中搬移去除，这样可以简化原有的类。有效地把类的核心职责和装饰功能区分开了。而且可以去除相关类中重复的装饰逻辑。