2.5 工厂方法

1.定义
创建对象的工作由工厂完成。

2.优点
屏蔽对象创建的复杂过程，让用户直接使用对象。

3.代码示例

public abstract class Video {
    abstract void produce();
}

public class JavaVideo extends Video {
    @Override
    void produce() {
        System.out.println("录制Java视频");
    }
}

public class PythonVideo extends Video{
    @Override
    void produce() {
        System.out.println("录制Python视频");
    }
}

public abstract class VideoFactory {
    abstract Video getVideo() ;
}

public class JavaVideoFactory extends VideoFactory{
    @Override
    Video getVideo() {
        return new JavaVideo();
    }
}

public class PythonVideoFactory extends VideoFactory{
    @Override
    Video getVideo() {
        return new PythonVideo();
    }
}

public class Test {
    public static void main(String[] args) {
        VideoFactory videoFactory = new JavaVideoFactory();
        Video video = videoFactory.getVideo();
        video.produce();
    }
}

4.源码解析

public interface Collection<E> extends Iterable<E> {
  Iterator<E> iterator();
}

public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable {
  public Iterator<E> iterator() {
    return new Itr();
  }
  
  private class Itr implements Iterator<E> {
    ......
  }
}