十一、结构型 外观模式（Facade Pattern）

外观模式（Facade Pattern）隐藏系统的复杂性，并向客户端提供了一个客户端可以访问系统的接口。这种类型的设计模式属于结构型模式，它向现有的系统添加一个接口，来隐藏系统的复杂性。

形状接口

public interface Shape {
    
    void draw();
}

形状实现类

public class Square implements Shape {

    @Override
    public void draw() {
        System.out.println("形状：正方形");
    }
}

public class Rectangle implements Shape {

    @Override
    public void draw() {
        System.out.println("形状：长方形");
    }
}

public class Circle implements Shape {

    @Override
    public void draw() {
        System.out.println("形状：圆");
    }
}

外观类

public class ShapeMaker {

    
    private Shape circle;
    
    private Shape rectangle;
    
    private Shape square;

    public ShapeMaker() {
        circle = new Circle();
        rectangle = new Rectangle();
        square = new Square();
    }

    public void drawCircle() {
        circle.draw();
    }

    public void drawRectangle() {
        rectangle.draw();
    }

    public void drawSquare() {
        square.draw();
    }
}

测试类

public class FacadePatternDemo {

    public static void main(String[] args) {
        ShapeMaker shapeMaker = new ShapeMaker();

        shapeMaker.drawCircle();
        shapeMaker.drawRectangle();
        shapeMaker.drawSquare();
    }

}

结果：

形状：圆
形状：长方形
形状：正方形

参考：
https://www.runoob.com/design-pattern/design-pattern-intro.html