裝飾器模式

1.裝飾器模式的定義

動態地給一個對象添加一些額外的職責。就增加功能來說，裝飾模式比生成子類更爲靈活

2.裝飾器模式的UML圖

Component：組件對象的接口，可以給這些對象動態的添加職責

ConcreteComponent：具體的組件對象，實現組件對象接口，通常就是被裝飾器裝飾的原始對象，也就是可以給這個對象添加職責

Decorator：所有裝飾器的抽象父類，需要定義一個與組件接口一致的接口，並持有一個Component對象，其實就是持有一個被裝飾的對象

3.代碼實現

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

public class ConcreteComponent extends Component{
   public void operation(){
   
   }
}


public abstract class Decorator extends Component
{
	protected Component component;
	public Decorator(Component component){
	      this.component=component;
	}

	public void operation(){
	   this.component.operation();
	
	}
}


public class ConcreteDecoratorA extends Decorator
{
   private String addedState;
   public String getAddedState(){
      return this.addedState;
   }

   public void setAddedState(String addedState){
       this.addedState=addedState;
   }

    public ConcreteDecoratorA(Component component){
	        this.component=component;
	}

	public void operation(){
	    this.component=compnent;
	}
}



public class ConcreteDecoratorB extends Decorator
{
   private String addedState;
   public String getAddedState(){
      return this.addedState;
   }

   public void setAddedState(String addedState){
       this.addedState=addedState;
   }

    public ConcreteDecoratorB(Component component){
	        this.component=component;
	}

	public void operation(){
	    this.component=compnent;
	}
}


public class  Client
{
	public static void main(String[] args){
	    Component component=new ConreteComponent();
		Decorator decorator=new ConcreteDecoratorA(component);
		decorator.operation();
	}
}

4.裝飾模式的本質：動態組合