设计模式-装饰者模式

结构图：

实现：

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

public class ConcreteComponent extends Component {

    @Override
    public void operation() {
        System.out.println("具体操作");
    }

}

public class Decorator extends Component{
    protected Component component;
    
    public void setComponent(Component c)
    {
        component = c;
    }

    @Override
    public void operation() {
        if (component != null)
            component.operation();
    }

}

public class ConcreteDecoratorA extends Decorator{

    @Override
    public void operation() {
        super.operation();
        
        System.out.println("增加装饰A的操作");
    }
    

}

public class ConcreteDecoratorB extends Decorator{

    @Override
    public void operation() {
        super.operation();
        
        System.out.println("增加装饰B的操作");
    }
    

}

public class Client {
    public static void main(String[] args)
    {
        ConcreteComponent cc = new ConcreteComponent();
        ConcreteDecoratorA cda = new ConcreteDecoratorA();
        ConcreteDecoratorB cdb = new ConcreteDecoratorB();
        
        cda.setComponent(cc);
        cdb.setComponent(cda);
        cdb.operation();
        
    }
}

应用场景：

适应于给一个对象动态添加额外的功能。