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装饰模式是对对象功能的扩展的一种模式，好处在于不更改原有对象的特性，只是通过注入方式为对象添加一些额外的功能，使得对象的功能丰富，特别有利于对对象行为的多个细小行为的添加。装饰模式是一种结构型模式。 装饰模式类图： [img]http://dl.iteye.com/upload/attachment/364545/b30e222f-1f5e-3ad1-a21f-ff3cec6723b6.jpg[/img] 具体demo示例： //组件抽象类

package decoratorPattern; public abstract class Component {
  	public abstract void doSomething(); }

具体实现：

package decoratorPattern; public class ConcreteComponent extends Component{
  	@Override 	public void doSomething() {
  		System.out.println("welcome to Taobao."); 	} }

装饰者：

package decoratorPattern; public abstract class Decorator extends Component{
  	private Component component; 	public abstract void doSomeDecoratorThing(); 	public void doSomething(){
  		doSomeDecoratorThing(); 		component.doSomething(); 	} 	public void setComponent(Component component) {
  		this.component = component; 	} }

具体装饰者1：

package decoratorPattern; public class ConcreteDecoratorA extends Decorator {
  	@Override 	public void doSomeDecoratorThing() {
  		System.out.println("Morning,"); 	} }

具体装饰者2：

package decoratorPattern; public class ConcreteDecoratorB extends Decorator{
  	@Override 	public void doSomeDecoratorThing() {
  		System.out.println("Afternoon,"); 	} }

测试类：

package decoratorPattern; public class decoratorPatternTest {
  	public static void main(String[]args){
  		Component component = new ConcreteComponent(); 		System.out.println("-----------------------------"); 		component.doSomething(); 		System.out.println("-----------------------------"); 		ConcreteDecoratorA concreteDecoratorA =new ConcreteDecoratorA(); 		concreteDecoratorA.setComponent(component); 		concreteDecoratorA.doSomething(); 		System.out.println("-----------------------------"); 		ConcreteDecoratorB concreteDecoratorB =new ConcreteDecoratorB(); 		concreteDecoratorB.setComponent(component); 		concreteDecoratorB.doSomething(); 	} }

说明：和直接子类相比，利用装饰者的话，能够更灵活的丰富对象的行为。

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