大话设计模式--装饰模式

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();    }}