2、抽象工厂模式

对工厂模式的形状实例进行扩展，增加颜色填充功能。

类图

• 形状和颜色接口

public interface Color {
    void fill();
}
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public interface Shape {
    void draw();
}

• 颜色实现类（形状的实现类上一篇有）

public class Blue implements Color{
    @Override
    public void fill() {
        System.out.println("fill Blue color!");
    }
}
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public class Red implements Color{
    @Override
    public void fill() {
        System.out.println("fill Red color!");
    }
}
------------------------------------------------------
public class Yellow implements Color{
    @Override
    public void fill() {
        System.out.println("fill Yellow color!");
    }
}

• 为 Color 和 Shape 对象创建抽象类来获取工厂

public interface AbstractFactory {
    Color getColor(String color);
    Shape getShape(String shape);
}

• 创建扩展了 AbstractFactory 的工厂类，基于给定的信息生成实体类的对象

public class ColorFactory implements AbstractFactory{

    @Override
    public Color getColor(String color) {
        if(color == null){
            return null;
        }
        if(color.equalsIgnoreCase("RED")){
            return new Red();
        } else if(color.equalsIgnoreCase("YELLOW")){
            return new Yellow();
        } else if(color.equalsIgnoreCase("BLUE")){
            return new Blue();
        }
        return null;
    }

    @Override
    public Shape getShape(String shape) {
        return null;
    }
}
----------------------------------------------------------------------------------
public class ShapeFactory implements AbstractFactory{

    @Override
    public Color getColor(String color) {
        return null;
    }

    @Override
    public Shape getShape(String shape) {
        if(shape == null){
            return null;
        }
        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;
    }
}

• 创建一个工厂创造器/生成器类，通过传递形状或颜色信息来获取工厂

public class FactoryProducer {
    public static AbstractFactory getFactory(String choice){
        if(choice.equalsIgnoreCase("SHAPE")){
            return new ShapeFactory();
        } else if(choice.equalsIgnoreCase("COLOR")){
            return new ColorFactory();
        }
        return null;
    }
}

• 使用 FactoryProducer 来获取 AbstractFactory，通过传递类型信息来获取实体类的对象

public class AbstractFactoryPatternDemo {
    public static void main(String[] args) {
        AbstractFactory colorFatory = FactoryProducer.getFactory("color");
        Color red = colorFatory.getColor("red");
        red.fill();
        Color yellow = colorFatory.getColor("yellow");
        yellow.fill();
        Color blue = colorFatory.getColor("blue");
        blue.fill();

        AbstractFactory shapeFactory = FactoryProducer.getFactory("shape");
        Shape rectangle = shapeFactory.getShape("rectangle");
        rectangle.draw();
        Shape circle = shapeFactory.getShape("circle");
        circle.draw();
        Shape square = shapeFactory.getShape("square");
        square.draw();
    }
}

• 输出结果：

fill Red color!
fill Yellow color!
fill Blue color!
Draw Rectangle!
Draw Circle!
Draw Square!