UML类图： 

组成部分： 
抽象构件：原始的功能接口 
具体构件：具体的原始功能类 
装饰角色：持有具体构件类的对象，以便执行原有功能 
具体装饰：具体扩展的功能在这里 

下面看一个人物功能拓展的实例（姓名+爱好）：

package com.dashu.decorator;

/**
 * 抽象接口类
 * */
public interface Component {
	public void operation();  
}

package com.dashu.decorator;

/**
 * 具体构建
 * */
public class ConcreteComponent implements Component {
	public ConcreteComponent() {
	}

	@Override
	public void operation() {
		// TODO Auto-generated method stub
		System.out.println("我的名字叫大树！");
	}

}

package com.dashu.decorator;

/**
 * 装饰角色，持有一个构件（Component）对象的实例，并定义一个与抽象构件接口一致的接口
 * */
public class Decorator implements Component {
	private Component component;

	public Decorator(Component component) {
		this.component = component;
	}

	@Override
	public void operation() {
		// TODO Auto-generated method stub
		component.operation();
	}

}

package com.dashu.decorator;

public class ConcreteDecorator extends Decorator {

	public ConcreteDecorator(Component component) {
		super(component);
	}

	@Override
	public void operation() {
		// TODO Auto-generated method stub
		super.operation();
		this.addedOperation();
	}

	public void addedOperation() {
		System.out.println("我爱好是编程！");
	}
}

package com.dashu.client;

import com.dashu.decorator.Component;
import com.dashu.decorator.ConcreteComponent;
import com.dashu.decorator.ConcreteDecorator;
import com.dashu.decorator.Decorator;

public class Client {
	public static void main(String[] args) {  
		Component component=new ConcreteComponent();
		Decorator decorator =new ConcreteDecorator(component);
		//客户端不变，但是已经添加了职责
		decorator.operation();
	}
}

Java装饰模式,布布扣,bubuko.com

Java装饰模式