工厂模式示例

把Thinking in java 中的一个示例整合的改写了一下，其中也涉及到泛型的一点知识：

package factoryinfo;
import java.util.*;
 interface Factory<T> {
 T create(); 
}
class Part{
 public String toString(){
  return getClass().getSimpleName();
  
   }
   static List<Factory<? extends Part>> partFactories=new ArrayList<Factory<? extends

Part>>();
   static {
    partFactories.add(new FuelFilter.Factory());
    partFactories.add(new AirFilter.Factory());
    partFactories.add(new CabinAirFilter.Factory());
    partFactories.add(new OilFilter.Factory());
    partFactories.add(new FanBelt.Factory());
    partFactories.add(new PowerSteeringBelt.Factory());
    partFactories.add(new GeneratorBelt.Factory());
    
   }
   private static Random rand =new Random(47);
   public static Part createRandom(){
    int n=rand.nextInt(partFactories.size());
    return partFactories.get(n).create();
   }
}
class Filter extends Part{}
class FuelFilter extends Filter{
 public static class Factory implements factoryinfo.Factory<FuelFilter>{
  public FuelFilter create(){
   return new FuelFilter();
  }
  
 }
}
class AirFilter extends Filter{
 public static class Factory implements  factoryinfo.Factory<AirFilter>{
  public AirFilter create(){
   return new AirFilter();
  }
 }
}

class CabinAirFilter extends Filter{
 public static class Factory implements  factoryinfo.Factory<CabinAirFilter>{
  public  CabinAirFilter create(){
   return new CabinAirFilter();
  }
 }
}

class OilFilter extends Filter{
 public static class Factory implements  factoryinfo.Factory<OilFilter>{
  public OilFilter create(){
   return new OilFilter();
  }
 }
}

class Belt extends  Part{}
class FanBelt extends Belt{
 public  static class Factory implements  factoryinfo.Factory<FanBelt>{
  public FanBelt create(){
   return new FanBelt();
  }
 }
}

class GeneratorBelt extends Belt{
 public static class Factory implements factoryinfo.Factory<GeneratorBelt>{
  public GeneratorBelt create(){
   return new GeneratorBelt();
  }
 }
 
}
class PowerSteeringBelt extends  Belt{
 public static class Factory implements  factoryinfo.Factory<PowerSteeringBelt>{
  public PowerSteeringBelt create(){
   return new PowerSteeringBelt();
  }
   
 }
}

public class RegisteredFactories {
 
 /**
  * Method main
  *
  *
  * @param args
  *
  */
 
  // TODO:
  public static void main(String[] args){
   for(int i=0;i<10;i++){
    System.out.println(Part.createRandom());
   }
  }
}