工厂方法

Posted 2021-01-31 linbq1911

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

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public abstract class Video {
4     public abstract void produce();
5 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class JavaVideo extends Video {
4     public void produce() {
5         System.out.println("录制Java课程视频");
6     }
7 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class PythonVideo extends Video {
4     public void produce() {
5         System.out.println("录制Python课程视频");
6     }
7 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class FEVideo extends Video {
4     @Override
5     public void produce() {
6         System.out.println("录制FE课程视频");
7     }
8 }

 1 package com.geely.design.pattern.creational.factorymethod;
 2 
 3 public abstract class VideoFactory {
 4 
 5     public abstract Video getVideo();
 6     /*public Video getVideo(String type){
 7         if("java".equalsIgnoreCase(type)){
 8             return new JavaVideo();
 9         }else if("python".equalsIgnoreCase(type)){
10             return new PythonVideo();
11         }
12         return null;
13     }*/
14 
15     /*public Video getVideo(Class clazz){
16         Video video = null;
17         try{
18             video = (Video) Class.forName(clazz.getName()).newInstance();
19         }catch(InstantiationException e){
20             e.printStackTrace();
21         }catch(IllegalAccessException e){
22             e.printStackTrace();
23         }catch(ClassNotFoundException e){
24             e.printStackTrace();
25         }
26         return video;
27     }*/
28 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class JavaVideoFactory extends VideoFactory {
4     @Override
5     public Video getVideo() {
6         return new JavaVideo();
7     }
8 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class PythonVideoFactory extends VideoFactory {
4     @Override
5     public Video getVideo() {
6         return new PythonVideo();
7     }
8 }

1 package com.geely.design.pattern.creational.factorymethod;
2 
3 public class FEVideo extends Video {
4     @Override
5     public void produce() {
6         System.out.println("录制FE课程视频");
7     }
8 }

 1 package com.geely.design.pattern.creational.factorymethod;
 2 
 3 public class Test {
 4     public static void main(String[] args) {
 5 
 6        VideoFactory videoFactory = new JavaVideoFactory();
 7        Video video = videoFactory.getVideo();
 8        video.produce();
 9        VideoFactory videoFactory2 = new PythonVideoFactory();
10        Video video2 = videoFactory2.getVideo();
11        video2.produce();
12         VideoFactory videoFactory3 = new FEVideoFactory();
13         Video video3 = videoFactory3.getVideo();
14         video3.produce();
15     }
16 }