Decorator模式

interface IService {
	public void execute();
}
public class Decorator implements IService {

	private IService service;
	public Decorator(IService service) {
		this.service = service;
	}
	
	@Override public void execute() {
		this.doSomething();
		this.service.execute();
	}
	
	private void doSomething() {
		System.out.println("Decorator.doSomething is running......");
	}

	public static void main(String[] args) {
		
		IService service = new AnotherDecorator(new Decorator(new ServiceImpl()));
		service.execute();
	}
}
class AnotherDecorator implements IService {
	
	private IService service;
	public AnotherDecorator(IService service) {
		this.service = service;
	}
	
	@Override public void execute() {
		this.service.execute();
		this.doOtherthing();
	}
	
	private void doOtherthing() {
		System.out.println("AnotherDecorator.doOtherthing is running......");
	}
}

 输出为：

ServiceImpl is create
Decorator.doSomething is running......
ServiceImpl.service is running......
AnotherDecorator.doOtherthing is running......

 

 

 * java io 流转换操作使用的是Decorator模式

 * 在不影响目标类其他对象的情况下，以动态、透明的方式给单个对象添加职责。

   处理那些可以撤消的职责。
 
 * 多个Decorator和目标类必须实现的是同一个接口或者基类，必须持有接口或者基类类型的实例。

 * Facade模式注重简化接口，Adapter模式注重转换接口，Bridge模式注重分离接口（抽象）与其实现，

   Decorator模式注重稳定接口的前提下为对象扩展功能。