Decorator装饰器，就是动态地给一个对象添加一些额外的职责，该对象与装饰器对象需要实现同一个接口，装饰器在方法实现里调用目标对象的方法实现并加入额外的操作。
将复杂的功能细化，分散到不同的装饰器中，然后根据需要动态的组合这些功能。
装饰器跟被目标对象都需实现的接口：
public interface Component { public void operation(); }
真正的实现类：
public class ConcreteComponent implements Component { @Override public void operation() { System.out.println("I am doing the real thing"); } }
装饰器A：
public class DecoratorA implements Component { private Component component; public DecoratorA(Component component) { super(); this.component = component; } @Override public void operation() { component.operation(); System.out.println("I am doing the extra thing A"); } }
装饰器B：
public class DecoratorB implements Component { private Component component; public DecoratorB(Component component) { super(); this.component = component; } @Override public void operation() { component.operation(); System.out.println("I am doing the extra thing B"); } }
客户端：
public static void main(String[] args) { Component component = new DecoratorB(new DecoratorA(new ConcreteComponent())); component.operation(); }
运行结果：
I am doing the real thing
I am doing the extra thing A
I am doing the extra thing B
原文：http://www.cnblogs.com/longzhaoyu/p/4211691.html