装饰者模式

装饰者模式

 动态地将责任附加到对象上。若要扩展功能，装饰者提供了比继承更有弹性的替代方案

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 看了以上四张图片之后，觉得是不是很晕呢？

不要紧，接下来看看代码：

 

 

 

package com.disign.decorator;

/**
 * 抽象组件
 * @author Administrator
 *
 */
public abstract class Beverage {

	String description = "Unknown Beverage";

	public String getDescription() {
		return description;
	}
	
	public abstract double cost();

}

package com.disign.decorator;


package com.disign.decorator;


/**
 * 具体组件 浓咖啡
 * @author Administrator
 *
 */
public class Espresso extends Beverage {
	
	public Espresso(){
		description = "Espresso";
	}

	@Override
	public double cost() {
		return 1.99;
	}

}

package com.disign.decorator;

/**
 * 具体组件 家常咖啡
 * @author Administrator
 *
 */
public class HouseBlend extends Beverage {
	
	public HouseBlend(){
		description = "House Blend coffee";
	}

	@Override
	public double cost() {
		return 0.89;
	}

}


package com.disign.decorator;

/**
 * 摩卡 (调料装饰者)
 * @author Administrator
 *
 */
public class Mocha extends CondimentDecorator {
	
	
	
	Beverage beverage;
	
	public Mocha(Beverage beverage){
		this.beverage = beverage;
	}

	@Override
	public String getDescription() {
		return beverage.getDescription()+",Mocha";
	}

	@Override
	public double cost() {
		return 0.20+beverage.cost();
	}

}

package com.disign.decorator;

/**
 * 豆浆 装饰者
 * @author Administrator
 *
 */
public class Soy extends CondimentDecorator {
	
	Beverage beverage;
	
	public Soy(Beverage beverage){
		this.beverage = beverage;
	}

	@Override
	public String getDescription() {
		return beverage.description+",Soy";
	}

	@Override
	public double cost() {
		return 0.11+beverage.cost();
	}

}



package com.disign.decorator;

public class Test {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		
		Beverage beverage1 = new Espresso();
		System.out.println(beverage1.getDescription()
				+"$"+beverage1.cost());
		
		Beverage beverage3 = new HouseBlend();
		beverage3 = new Soy(beverage3);
		beverage3 = new Mocha(beverage3);
		System.out.println(beverage3.getDescription()
				+"$"+beverage3.cost());
		
		

	}

}

 

看了之后，我觉得这里面有几个概念了，组合、继承、委托、装饰者、被装饰者、静态调用、运行时动态调用

理解这些，我觉得这个装饰者模式就开始清楚点了