10) Decorator Pattern

类别：

 Structural Pattern

问题：

 在不改变接口的前提下增加额外的服务

方案：

示例：

public class DecoratorPatternDemo {
    public static void main(String[] args) {
        Shape circle = new Circle();
        Shape redCircle = new RedShapeDecorator(new Circle());
        Shape redRectangle = new RedShapeDecorator(new Rectangle());
        System.out.println("普通圆");
        circle.draw();
        System.out.println("\n红框圆");
        redCircle.draw();
        System.out.println("\n红框矩形");
        redRectangle.draw();
    }
}

interface Shape {
    void draw();
}

class Rectangle implements Shape {
    @Override
    public void draw() {
        System.out.println("Shape: Rectangle");
    }
}

class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println("Shape: Circle");
    }
}

abstract class ShapeDecorator implements Shape {
    protected Shape shap;

    public ShapeDecorator(Shape shap) {
        this.shap = shap;
    }

    public abstract void draw();
}

class RedShapeDecorator extends ShapeDecorator {
    public RedShapeDecorator(Shape shap) {
        super(shap);
    }

    @Override
    public void draw() {
        shap.draw();
        setRedBorder(shap);
    }

    private void setRedBorder(Shape decoratedShape) {
        System.out.println("Border Color: Red");
    }
}

普通圆
Shape: Circle

红框圆
Shape: Circle
Border Color: Red

红框矩形
Shape: Rectangle
Border Color: Red

应用：

不足：(

优化：）