大话设计模式--装饰模式

Posted 2022-12-09 程序员小熊

装饰模式：动态地给一个对象添加一些额外的职责，就增加功能来说，装饰模式比生成子类更加灵活。

Component是定义了一个对象接口，可以给这些对象动态地添加职责，ConcreteComponent是定义了一个具体的对象，也可以给这些对象添加一些职责。Decorator，装饰抽象类，继承了Component，从外类来扩展Component类的功能，但对于Component来说，是无需知道Decorator的存在的，至于ConcreteDecorator就是具体的装饰对象，起到给Component添加职责的功能。

public abstract class Component 

    public abstract void Operation();

public class ConcreteComponent extends Component 

    @Override
    public void Operation() 

    

public abstract class Decorator extends Component 

    protected Component component;

    public void setComponent(Component component) 
        this.component = component;
    

    @Override
    public void Operation() 
        if (component != null) 
            component.Operation();
        
    

public class ConcreteDecoratorA extends Decorator 

    private String addedState;

    @Override
    public void Operation() 
        super.Operation();
        addedState = "New State";
        System.out.println("对具体对象A的操作");
    

public class ConcreteDecoratorB extends Decorator 

    @Override
    public void Operation() 
        super.Operation();
        AddedBehavior();
        System.out.println("具体装饰对象B的操作");
    

    private void AddedBehavior() 

    

public class Main 

    public static void main(String[] args) 
        ConcreteComponent c = new ConcreteComponent();
        ConcreteDecoratorA decoratorA = new ConcreteDecoratorA();
        ConcreteDecoratorB decoratorB = new ConcreteDecoratorB();

        decoratorA.setComponent(c);
        decoratorB.setComponent(decoratorA);
        decoratorB.Operation();