设计模式

public interface Shape {
    void draw();
}

public class Rectangle implements Shape{
    @Override
    public void draw() {
        System.out.println("我画出了一个矩形");
    }
}

public class Circle implements Shape{
    @Override
    public void draw() {
        System.out.println("我画出了一个圆");
    }
}

public class Square implements Shape {
    @Override
    public void draw() {
        System.out.println("我画出了一个正方形");
    }
}

public class ShapeFactory {
    public Shape getShape(String shape){
        if(shape == null){
            return null;
        }else if(shape.equalsIgnoreCase("Circle")){
            return new Circle();
        }else if(shape.equalsIgnoreCase("Rectangle")){
            return new Rectangle();
        }else if(shape.equalsIgnoreCase("Square")){
            return new Square();
        }
        return null;
    }
}

public class TestShape {
    public static void main(String[] args){
        ShapeFactory sf = new ShapeFactory();
        Shape shape1 = sf.getShape("Circle");
        shape1.draw();
        Shape shape2 = sf.getShape("Rectangle");
        shape2.draw();
        Shape shape3 = sf.getShape("Square");
        shape3.draw();
    }
}