java設計模式:裝飾者模式

1.裝飾模式就是給一個對象增加一些新的功能，而且是動態的，要求裝飾
對象和被裝飾對象實現同一個接口，裝飾對象持有被裝飾對象的實例.
2.裝飾器模式的應用場景：擴展一個類的功能.
3.整體模式的設計;
(1).裝飾者和被裝飾者都要繼承的抽象類Drink()
(2).裝飾者:Decorator(), 和繼承裝飾者的具體實現類
(3).被裝飾的對象Coffee(), 和繼承Coffee的對象
4.具體代碼:
(1).
/**
* 裝飾對象 和 被裝飾對象 繼承的同一個的類 即:裝飾者:Decorator, 被裝飾着:Drink
*/
public abstract class Drink {

public String description="";
private float price=0f;;

public void setDescription(String description)
{
    this.description=description;
}

public String getDescription()
{
    return description+"-"+this.getPrice();
}
public float getPrice()
{
    return price;
}
public void setPrice(float price)
{
    this.price=price;
}
public abstract float cost();

}
(2).
/**
* 被裝飾者– 繼承Drink實體類 和Decorator一樣都是繼承Drink實體類
*/
public class Coffee extends Drink {

@Override
public float cost() {
    return super.getPrice();
}

}
具體的被裝飾的對象:
public class Decaf extends Coffee {

public Decaf()
{
    super.setDescription("Decaf");
    super.setPrice(3.0f);
}

}
public class Espresso extends Coffee{

public Espresso()
{
    super.setDescription("Espresso");
    super.setPrice(4.0f);
}

}
public class LongBlack extends Coffee{

public LongBlack()
{
    super.setDescription("LongBlack");
    super.setPrice(6.0f);
}

}
等等……….

(3).
/**
* 裝飾者– 繼承Drink實體類 和Coffe一樣都是繼承Drink實體類
*/
public class Decorator extends Drink {

private Drink Obj;

public Decorator(Drink Obj){
    this.Obj=Obj;
};


@Override
public float cost() {
    return super.getPrice()+Obj.cost();
}

@Override
public String getDescription()
{
    return super.description+"-"+super.getPrice()+"&&"+Obj.getDescription();
}

}

//具體繼承的
public class Milk extends Decorator {

public Milk(Drink Obj) {
    super(Obj);
    super.setDescription("Milk");
    super.setPrice(2.0f);
}

}
public class Chocolate extends Decorator {

public Chocolate(Drink Obj) {
    super(Obj);
    super.setDescription("Chocolate");
    super.setPrice(3.0f);
}

}
public class Soy extends Decorator {

public Soy(Drink Obj) {
    super(Obj);
    // TODO Auto-generated constructor stub
    super.setDescription("Soy");
    super.setPrice(1.5f);
}

}

測試:
public static void main(String[] args) {

    Drink order;
    order=new Decaf();
    System.out.println("order1 price:"+order.cost());
    System.out.println("order1 desc:"+order.getDescription());

    System.out.println("****************");
    order=new LongBlack();
    order=new Milk(order);

    order=new Chocolate(order);
    order=new Chocolate(order);

    System.out.println("order2 price:"+order.cost());
    System.out.println("order2 desc:"+order.getDescription());

}