菜鸟硕枫设计模式系列之10 装饰模式

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。