工厂方法

1.定义：定义一个创建对象的接口，但让实现这个接口的类来决定实例化哪个类，工厂方法让类的实例化推迟到子类中进行

2.类型：创建型

3.适用场景：创建对象需要大量重复的代码，客户端(应用层)不依赖于产品类的实例如何被创建、实现等细节，

　　　　　   一个类通过其子类来指定创建哪个对象

4.优点：用户只需要关心所需产品对应的工厂，无须关心创建细节；加入新产品符合开闭原则，提高可扩展性

5.缺点：类的个数容易过多，增加复杂度；增加了系统的抽象性和理解难度

6.实例目录package

7.实例UML类图

8.代码

package com.geely.design.pattern.creational.factorymethod;

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

package com.geely.design.pattern.creational.factorymethod;

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

package com.geely.design.pattern.creational.factorymethod;

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

package com.geely.design.pattern.creational.factorymethod;

public class FEVideo extends Video {
    @Override
    public void produce() {
        System.out.println("录制FE课程视频");
    }
}

package com.geely.design.pattern.creational.factorymethod;

public abstract class VideoFactory {

    public abstract Video getVideo();
    /*public Video getVideo(String type){
        if("java".equalsIgnoreCase(type)){
            return new JavaVideo();
        }else if("python".equalsIgnoreCase(type)){
            return new PythonVideo();
        }
        return null;
    }*/

    /*public Video getVideo(Class clazz){
        Video video = null;
        try{
            video = (Video) Class.forName(clazz.getName()).newInstance();
        }catch(InstantiationException e){
            e.printStackTrace();
        }catch(IllegalAccessException e){
            e.printStackTrace();
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }
        return video;
    }*/
}

package com.geely.design.pattern.creational.factorymethod;

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

package com.geely.design.pattern.creational.factorymethod;

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

package com.geely.design.pattern.creational.factorymethod;

public class FEVideo extends Video {
    @Override
    public void produce() {
        System.out.println("录制FE课程视频");
    }
}

package com.geely.design.pattern.creational.factorymethod;

public class Test {
    public static void main(String[] args) {

       VideoFactory videoFactory = new JavaVideoFactory();
       Video video = videoFactory.getVideo();
       video.produce();
       VideoFactory videoFactory2 = new PythonVideoFactory();
       Video video2 = videoFactory2.getVideo();
       video2.produce();
        VideoFactory videoFactory3 = new FEVideoFactory();
        Video video3 = videoFactory3.getVideo();
        video3.produce();
    }
}