面向对象的设计模式 ——装饰模式

装饰模式：（继承过来，重写方法的时候调用原有方法和添加自己的装饰方法或代码）

好处就是把类的核心功能和装饰功能分开，而且如果想要再添加装饰功能不需要反反复复的的修改原来的类

abstract class Component{
    public abstract void Operation();
}

class ConcreteComponent extends Component{
    public void Operation(){
        System.out.println("具体对象的操作");
    }
}

abstract class Decorator extends Component{
    protected Component component;

    public void SetComponent(Component component)
    {
        this.component = component;
    }

    public void Operation(){
        if(component != null){
            component.Operation();
        }
    }
}

class ConcreteDecoratorA extends Decorator{
    private string addedState;
    
    public void Operation(){
        super.Operation();
        addedState = "New State";
        System.out.println("具体装饰对象A的操作");
    }
}

class ConcreteDecoratorB extends Decorator{
    
    public void Operation(){
        super.Operation();
        AddedBehavior();
        System.out.println("具体装饰对象B的操作");
    }
    
    private void AddedBehavior(){
    }
}

public test{
    public static void main(String args[]){
        ConcreteComponent c = new ConcreteComponent();
        ConcreteDecoratorA d1 = new ConcreteDecoratorA();
        ConcreteDecoratorB d2 = new ConcreteDecoratorB();

        d1.SetComponent(c);
        d2.SetComponent(d1);
        d2.Operation();

    }
}

 最后的输出应该是

具体对象的操作

具体装饰对象A的操作

具体装饰对象B的操作