Java 装饰者模式 —— { }

被装饰者接口

//被装饰者的接口
public interface Drink {

	float cost();			//计算价格
	String description();	//描述
	
}

具体的被装饰者

public class SoyaBeanMilk implements Drink{

	@Override
	public float cost() {
		return 10f;
	}

	@Override
	public String description() {
		return "纯豆浆";
	}

}

装饰者基类

public abstract class Decorator implements Drink{

	private Drink drink;				//要装饰的对象
	public Decorator(Drink drink){
		this.drink = drink;
	}
	@Override
	public float cost() {
		return drink.cost();
	}

	@Override
	public String description() {
		return drink.description();
	}
	
}

具体的装饰者_01

public class SugarDecorator extends Decorator {

	public SugarDecorator(Drink drink) {
		super(drink);
	}
	@Override
	public float cost() {
		return super.cost()+1.0f;
	}
	
	@Override
	public String description() {
		return super.description()+"+糖";
	}
	
}

具体的装饰者_02

public class BlackBeanDecorator extends Decorator {

	public BlackBeanDecorator(Drink drink) {
		super(drink);
	}
	@Override
	public float cost() {
		return super.cost()+2.0f;
	}
	
	@Override
	public String description() {
		return super.description()+"+黑豆";
	}

}

具体的装饰者_03

public class EggDecorator extends Decorator {

	public EggDecorator(Drink drink) {
		super(drink);
	}
	@Override
	public float cost() {
		return super.cost()+3.0f;
	}
	
	@Override
	public String description() {
		return super.description()+"+鸡蛋";
	}

}

测试类

public class Test {

	public static void main(String[] args) {
		
//		OutputStream out = new FileOutputStream("xxx");
//		BufferedOutputStream bos = new BufferedOutputStream(out);
//		PrintStream ps = new PrintStream(bos);
//		ps.print(..);

		Drink drink = new SoyaBeanMilk();
		SugarDecorator sugar = new SugarDecorator(drink);
		EggDecorator egg = new EggDecorator(sugar);
		BlackBeanDecorator blackBean = new BlackBeanDecorator(egg);
		
		System.out.println("你点的豆浆是："+blackBean.description());
		System.out.println("一共花了"+blackBean.cost()+"元");
	}

}

运行结果