裝飾者模式：動態的將新功能附加到對象上，在對象功能擴展方面，它比繼承更有彈性。
一、咖啡館訂單項目
1)、咖啡種類 : Espresso、ShortBlack、LongBlack、Decaf
2)、調料 : Milk、Soy、Chocolate
3)、擴展性好、改動方便、維護方便
下面這個方案會類爆炸：
二、裝飾者模式
1、Drink抽象類
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、Coffee類及其實現類
1）、Coffee基類
public class Coffee extends Drink {
@Override
public float cost() {
return super.getPrice();
}
}
2）、Decaf類
public class Decaf extends Coffee {
public Decaf()
{
super.setDescription("Decaf");
super.setPrice(3.0f);
}
}
3）、Espresso類
public class Espresso extends Coffee{
public Espresso(){
super.setDescription("Espresso");
super.setPrice(4.0f);
}
}
4）、LongBlack類
public class LongBlack extends Coffee{
public LongBlack(){
super.setDescription("LongBlack");
super.setPrice(6.0f);
}
}
3、Decorator類及其實現類
1）、Decorator基類
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();
}
}
2）、Chocolate類
public class Chocolate extends Decorator {
public Chocolate(Drink Obj) {
super(Obj);
super.setDescription("Chocolate");
super.setPrice(3.0f);
}
}
3）、Milk類
public class Milk extends Decorator {
public Milk(Drink Obj) {
super(Obj);
super.setDescription("Milk");
super.setPrice(2.0f);
}
}
4、Decorator類及其實現類
public class CoffeeBar {
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(); // 一杯黑咖啡
order=new Milk(order); // 一杯加牛奶的黑咖啡
order=new Chocolate(order); // 一杯加Chocolate加牛奶的黑咖啡
order=new Chocolate(order); // 一杯加兩份Chocolate加牛奶的黑咖啡
System.out.println("order2 price:"+order.cost());
System.out.println("order2 desc:"+order.getDescription());
}
}
