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设计模式之装饰器模式

简介:

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。

使用场景:

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。

类图:

技术分享

 

示例代码:

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

设计模式之装饰器模式