Head first笔记三：装饰者模式

public abstract class Beverage {
String description = “Unknown Beverage”;
public String getDescription() {
return description;
}
public abstract double cost();
}

public abstract class CondimentDecorator extends Beverage {
public abstract String getDescription();
}

public class Espresso extends Beverage {
public Espresso() {
description = “Espresso”;
}
public double cost() {
return 1.99;
}
}

public class HouseBlend extends Beverage {
public HouseBlend() {
description = “House Blend Coffee”;
}
public double cost() {
return .89;
}
}

public class Mocha extends CondimentDecorator {
Beverage beverage;
public Mocha(Beverage beverage) {
this.beverage = beverage;
}
public String getDescription() {
return beverage.getDescription() + “, Mocha”;
}
public double cost() {
return .20 + beverage.cost();
}
}

public class StarbuzzCoffee {
public static void main(String args[]) {
Beverage beverage = new Espresso();
System.out.println(beverage.getDescription()
+ “ $” + beverage.cost());
Beverage beverage2 = new DarkRoast();
beverage2 = new Mocha(beverage2);
beverage2 = new Mocha(beverage2);
beverage2 = new Whip(beverage2);
System.out.println(beverage2.getDescription()
+ “ $” + beverage2.cost());
Beverage beverage3 = new HouseBlend();
beverage3 = new Soy(beverage3);
beverage3 = new Mocha(beverage3);
beverage3 = new Whip(beverage3);
System.out.println(beverage3.getDescription()
+ “ $” + beverage3.cost());
}
}