14.4 注册工厂

工厂模式的变种：通过接口的形式来实现

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
class Part{
    @Override
    public String toString() {
        return getClass().getSimpleName();
    }
    static List<Factory<? extends Part>> partFactories = new ArrayList<Factory<? extends Part>>();
    static {
        //此时partFactories为类型信息
        partFactories.add(new FuelFiletr.Fac());
        partFactories.add(new AirFilter.Fac());
    }
    private static Random random = new Random(47);
    public static Part createRandom(){
        int i = random.nextInt(partFactories.size());
        return partFactories.get(i).create();
    }
}
class Filter extends Part{}
class FuelFiletr extends Filter{
    public static class Fac implements Factory<FuelFiletr>{
        @Override
        public FuelFiletr create() {
            return new FuelFiletr();
        }
    }
}
class AirFilter extends Filter{
    public static class Fac implements Factory<AirFilter>{
        @Override
        public AirFilter create() {
            return new AirFilter();
        }
    }
}
public class RegisterFactories {
    public static void main(String[] args) {
        for (int i = 0; i < 5; i++) {
            System.out.println(Part.createRandom());
        }
    }
}