工廠模式

public class Client {
   public static void main(String[] args){
       try{
           Car car = BMWFactory.produceCar();
           car.drive();
       }catch (Exception e){
           System.out.println(e.getMessage());
       }
   }
}

public interface CarFactory {
    public static Car produceCar() {
        return null;
    }
}

public class BMWFactory implements CarFactory{
    public static Car produceCar() {
        System.out.println("BMW汽車工廠正在製造汽車");
        return new BMWCar();
    }
}

public class QOROSFactory implements CarFactory{
    public static Car produceCar() {
        System.out.println("QOROS汽車工廠正在製造汽車");
        return new QOROSCar();
    }
}

public interface Car {
    public void drive();
}

public class BMWCar implements Car {
    public void drive(){
        System.out.println("BMW汽車正在行駛");
    }
}

public class QOROSCar implements Car{
    public void drive(){
        System.out.println("QOROS汽車正在行駛");
    }
}

缺點：當需要添加新的功能模塊時，雖然滿足了開閉原則，但每次添加一個功能模塊，需要添加兩個類，比較累贅。