装饰器模式

1、意图

动态增加功能，相比于继承更加灵活

2、类图

Component(VisualComponent)：定义一个对象接口，可以给这些对象动态地添加职责。ConcreteComponent(TextView)：定义一个对象，可以给这个对象添加一些职责。

Decorator：维持一个指向Component对象的指针，并定义一个与Component接口一致的接口。ConcreteDecorator(BorderDecorator、ScrollDecorator)：向组件添加职责。

3、实现

public interface Component {void draw();
}

public class ConcreteComponent implements Component{@Overridepublic void draw() {System.out.println("展示一个窗口");}
}

 抽象类实现接口

public abstract class Decorator implements Component{public Component component;Decorator(Component component){this.component=component;}@Overridepublic void draw() {component.draw();}
}

public class ConcreteDecorator1 extends Decorator{ConcreteDecorator1(Component component) {super(component);}@Overridepublic void draw() {System.out.println("给窗口加边框");super.draw();}
}

public class ConcreteDecorator2 extends Decorator{ConcreteDecorator2(Component component) {super(component);}@Overridepublic void draw() {System.out.println("给窗口加滚动条");super.draw();}
}

public class test {public static void main(String[] args) {Component concreteComponent=new ConcreteComponent();Decorator decorator1=new ConcreteDecorator1(concreteComponent);decorator1.draw();System.out.println("------------------------------");Decorator decorator2=new ConcreteDecorator2(concreteComponent);decorator2.draw();}
}

4、效果