设计模式（5）抽象工厂模式

抽象工厂，提供一个工厂接口，用于创建依赖对象的家族，不需要明确指定具体类。可以理解是多个工厂方法的组合。

例如一个款手机是有电池、相机、处理器、屏幕组成的，它其中包含了不同的对象，我们创建时需要创建多个不同类型的对象，而工厂方法只能创建一种类型的对象，满足不了这种需求。那我们可以把多个工厂方法组合到一起，用来创建多个产品。

首先我们先定义抽象工厂，他可以生产电池、相机、处理器、屏幕

public interface BasePhoneFactory {

    public BaseCamara createCamara();

    public BaseBattery createBattery();

    public BaseScreen createScreen();

    public BaseCpu createCpu();

}

然后创建各个抽象的产品

public interface BaseBattery {

    public void name();

}

public interface BaseCamara {
    
    public void name();
    
}

public interface BaseCpu {
    
    public void name();
    
}

public interface BaseScreen {
    
    public void name();
    
}

然后各个产品的实现类

public class Battery_3000 implements BaseBattery {
    @Override
    public void name() {
        System.out.println("3000毫安锂电池");
    }
}

public class Battery_3800 implements BaseBattery {
    @Override
    public void name() {
        System.out.println("3800毫安锂电池");
    }
}

public class Camara_1200 implements BaseCamara {
    @Override
    public void name() {
        System.out.println("1200W像素相机");
    }
}

public class Camara_1800 implements BaseCamara {
    @Override
    public void name() {
        System.out.println("1800W像素相机");
    }
}

public class Cpu_4_8 implements BaseCpu {
    @Override
    public void name() {
        System.out.println("4核8线程处理器");
    }
}

public class Cpu_6_12 implements BaseCpu {
    @Override
    public void name() {
        System.out.println("6核12线程处理器");
    }
}

public class Screen_1080 implements BaseScreen {
    @Override
    public void name() {
        System.out.println("1080P屏幕");
    }
}

public class Screen_1440 implements BaseScreen {
    @Override
    public void name() {
        System.out.println("1440P屏幕");
    }
}

现在就是我们工厂的创建了

public class PhoneFactory_2018 implements BasePhoneFactory {
    @Override
    public BaseCamara createCamara() {
        return new Camara_1200();
    }

    @Override
    public BaseBattery createBattery() {
        return new Battery_3000();
    }

    @Override
    public BaseScreen createScreen() {
        return new Screen_1080();
    }

    @Override
    public BaseCpu createCpu() {
        return new Cpu_4_8();
    }
}

public class PhoneFactory_2019 implements BasePhoneFactory {
    @Override
    public BaseCamara createCamara() {
        return new Camara_1800();
    }

    @Override
    public BaseBattery createBattery() {
        return new Battery_3800();
    }

    @Override
    public BaseScreen createScreen() {
        return new Screen_1440();
    }

    @Override
    public BaseCpu createCpu() {
        return new Cpu_6_12();
    }
}

下面是手机基类和它的实现类

public abstract class BasePhone {
    /**
     * 电池
     */
    protected BaseBattery battery;
    /**
     * 相机
     */
    protected BaseCamara camara;
    /**
     * 处理器
     */
    protected BaseCpu cpu;
    /**
     * 屏幕
     */
    protected BaseScreen screen;

    public void display() {
        battery.name();
        camara.name();
        cpu.name();
        screen.name();
    }

    public abstract void getPhone();
}

public class Phone_2018 extends BasePhone {

    BasePhoneFactory phoneFactory;

    public Phone_2018() {
        phoneFactory = new PhoneFactory_2018();
    }

    @Override
    public void getPhone() {
        this.camara = this.phoneFactory.createCamara();
        this.battery = this.phoneFactory.createBattery();
        this.cpu = this.phoneFactory.createCpu();
        this.screen = this.phoneFactory.createScreen();
    }

    @Override
    public void display() {
        System.out.println("2018年款手机");
        super.display();
    }
}

public class Phone_2019 extends BasePhone {

    BasePhoneFactory phoneFactory;

    public Phone_2019() {
        phoneFactory = new PhoneFactory_2019();
    }

    @Override
    public void getPhone() {
        this.camara = this.phoneFactory.createCamara();
        this.battery = this.phoneFactory.createBattery();
        this.cpu = this.phoneFactory.createCpu();
        this.screen = this.phoneFactory.createScreen();
    }

    @Override
    public void display() {
        System.out.println("2019年款手机");
        super.display();
    }
}

测试代码

public class Main {

    public static void main(String[] args) {
        BasePhone phone1 = new Phone_2018();
        phone1.getPhone();
        phone1.display();

        System.out.println("-------------------");

        BasePhone phone2 = new Phone_2019();
        phone2.getPhone();
        phone2.display();
    }
}

输出结果

抽象工厂一个具体的工厂就能创建出多个产品，和工厂方法相比，减少了具体工厂的数量。

但是，如果需要给抽象工厂中添加一个成员，就需要改动所有的工厂，扩展性就比较差了。