Design mode 2: factory mode

design mode factory mode


What is factory mode

Everyone should have used or seen it in the development SqlSessionFactory perhaps BeanFactory, This is using factory mode to produce objects . Objects for factory creation and management , Separate the creator and caller of the object , Achieve the goal of decoupling from objects .

The factory model can be divided into :

  • Simple factory
  • Factory method
  • Abstract factory

Realization way

Simple factory

Simple factory returns different object instances by receiving different parameters , The roles involved are :

  • Abstract product
  • Specific products
  • Specific factory
  • caller

The code is as follows :

// Abstract product
public interface Car {
void run();
}
// Specific products 1
public class Audi implements Car {
@Override
public void run() {
System.out.println("audi run");
}
}
// Specific products 2
public class Benz implements Car{
@Override
public void run() {
System.out.println("benz run");
}
}
// Specific factory , Used to build products
public class SimpleFactory {
// The way 1, Generate the corresponding product object according to the passed in parameters
public static Car getCar(String type){
if ("audi".equals(type)){
return new Audi();
} else if ("benz".equals(type)){
return new Benz();
} else {
return null;
}
}
// The way 2, Directly call the method that generates the corresponding product object
public static Car getAudi(){
return new Audi();
}
public static Car getBenz(){
return new Benz();
}
}
// caller
public class SimpleFactoryTest {
public static void main(String[] args) {
// There is no simple factory , Then the client needs to connect with the interface Car And its implementation
// Car audi = new Audi();
// Car benz = new Benz();
// audi.run();
// benz.run();
// Use a simple factory , The way 1
Car audi = SimpleFactory.getCar("audi");
Car benz = SimpleFactory.getCar("benz");
audi.run();
benz.run();
System.out.println("============");
// Use a simple factory , The way 2
Car audi1 = SimpleFactory.getAudi();
Car benz1 = SimpleFactory.getBenz();
audi1.run();
benz1.run();
}
}

The class diagram is as follows :

image

You can see , If you add another product , You need to modify the factory class , So this kind of factory mode is suitable for less product objects , And the product has a fixed demand . In fact, it is enough for us to use simple factories in general projects .

Factory method

In order to avoid the shortcomings of simple factories that do not meet the principle of opening and closing , Add products without modifying the factory class , You can use the factory method pattern , Add a corresponding factory class to produce corresponding products while adding products , The roles involved are :

  • Abstract product
  • Specific products
  • Abstract factory
  • Specific factory
  • caller

The code is as follows :

// Abstract product
public interface Car {
void run();
}
// Specific products 1
public class Audi implements Car {
@Override
public void run() {
System.out.println("audi run");
}
}
// Specific products 2
public class Benz implements Car {
@Override
public void run() {
System.out.println("benz run");
}
}
// Abstract factory
public interface CarFactory {
Car createCar();
}
// Specific factory 1
public class AudiFactory implements CarFactory {
@Override
public Car createCar() {
return new Audi();
}
}
// Specific factory 2
public class BenzFactory implements CarFactory {
@Override
public Car createCar() {
return new Benz();
}
}
// caller
public class FactoryMethodTest {
public static void main(String[] args) {
Car audi = new AudiFactory().createCar();
Car benz = new BenzFactory().createCar();
audi.run();
benz.run();
}
}

The class diagram is as follows :

image

You can see , If you add a specific product , We need to add a specific factory class to produce the product .

Abstract factory

Abstract factories are used to produce a family of products . The roles involved are :

  • Abstract product
  • Specific products
  • Abstract factory
  • Specific factory
  • caller

The code is as follows :

// Abstract product A
public interface Engine {
void autoStart();
}
// Specific products A1
public class HighEngine implements Engine {
@Override
public void autoStart() {
System.out.println(" High end engine has automatic start stop function ");
}
}
// Specific products A2
public class LowEngine implements Engine {
@Override
public void autoStart() {
System.out.println(" The low-end engine has no automatic start stop function ");
}
}
// Abstract product B
public interface Tyre {
void monitor();
}
// Specific products B1
public class HighTyre implements Tyre {
@Override
public void monitor() {
System.out.println(" High end tires have tire pressure monitoring function ");
}
}
// Specific products B2
public class LowTyre implements Tyre {
@Override
public void monitor() {
System.out.println(" Low end tires have no tire pressure monitoring function ");
}
}
// Abstract factory
public interface CarFactory {
Engine createEngine();
Tyre createTyre();
}
// Specific factory A1B1
public class HighCarFactory implements CarFactory {
@Override
public HighEngine createEngine() {
return new HighEngine();
}
@Override
public HighTyre createTyre() {
return new HighTyre();
}
}
// Specific factory A2B2
public class LowCarFactory implements CarFactory {
@Override
public LowEngine createEngine() {
return new LowEngine();
}
@Override
public LowTyre createTyre() {
return new LowTyre();
}
}
// caller
public class AbstractFactoryTest {
public static void main(String[] args) {
CarFactory highCar = new HighCarFactory();
highCar.createEngine().autoStart();
highCar.createTyre().monitor();
}
}

The class diagram is as follows :

image

You can see that through specific factories A1B1 and A2B2 Different product families can be produced , When the product is fixed , You can add a specific factory class , To combine and generate different product families , such as A1B2 perhaps A2B1. But if you want to add new products , Such as adding products C, Then we need to modify the abstract factory and the concrete factory , It doesn't fit .

Welcome to my official account. , Learn technology together .
image

版权声明
本文为[Program development and operation and maintenance]所创,转载请带上原文链接,感谢
https://javamana.com/2021/01/20210122173312862u.html

  1. 【计算机网络 12(1),尚学堂马士兵Java视频教程
  2. 【程序猿历程,史上最全的Java面试题集锦在这里
  3. 【程序猿历程(1),Javaweb视频教程百度云
  4. Notes on MySQL 45 lectures (1-7)
  5. [computer network 12 (1), Shang Xuetang Ma soldier java video tutorial
  6. The most complete collection of Java interview questions in history is here
  7. [process of program ape (1), JavaWeb video tutorial, baidu cloud
  8. Notes on MySQL 45 lectures (1-7)
  9. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  10. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  11. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  12. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  13. 【递归,Java传智播客笔记
  14. [recursion, Java intelligence podcast notes
  15. [adhere to painting for 386 days] the beginning of spring of 24 solar terms
  16. K8S系列第八篇(Service、EndPoints以及高可用kubeadm部署)
  17. K8s Series Part 8 (service, endpoints and high availability kubeadm deployment)
  18. 【重识 HTML (3),350道Java面试真题分享
  19. 【重识 HTML (2),Java并发编程必会的多线程你竟然还不会
  20. 【重识 HTML (1),二本Java小菜鸟4面字节跳动被秒成渣渣
  21. [re recognize HTML (3) and share 350 real Java interview questions
  22. [re recognize HTML (2). Multithreading is a must for Java Concurrent Programming. How dare you not
  23. [re recognize HTML (1), two Java rookies' 4-sided bytes beat and become slag in seconds
  24. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  25. RPC 1: how to develop RPC framework from scratch
  26. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  27. RPC 1: how to develop RPC framework from scratch
  28. 一次性捋清楚吧,对乱糟糟的,Spring事务扩展机制
  29. 一文彻底弄懂如何选择抽象类还是接口,连续四年百度Java岗必问面试题
  30. Redis常用命令
  31. 一双拖鞋引发的血案,狂神说Java系列笔记
  32. 一、mysql基础安装
  33. 一位程序员的独白:尽管我一生坎坷,Java框架面试基础
  34. Clear it all at once. For the messy, spring transaction extension mechanism
  35. A thorough understanding of how to choose abstract classes or interfaces, baidu Java post must ask interview questions for four consecutive years
  36. Redis common commands
  37. A pair of slippers triggered the murder, crazy God said java series notes
  38. 1、 MySQL basic installation
  39. Monologue of a programmer: despite my ups and downs in my life, Java framework is the foundation of interview
  40. 【大厂面试】三面三问Spring循环依赖,请一定要把这篇看完(建议收藏)
  41. 一线互联网企业中,springboot入门项目
  42. 一篇文带你入门SSM框架Spring开发,帮你快速拿Offer
  43. 【面试资料】Java全集、微服务、大数据、数据结构与算法、机器学习知识最全总结,283页pdf
  44. 【leetcode刷题】24.数组中重复的数字——Java版
  45. 【leetcode刷题】23.对称二叉树——Java版
  46. 【leetcode刷题】22.二叉树的中序遍历——Java版
  47. 【leetcode刷题】21.三数之和——Java版
  48. 【leetcode刷题】20.最长回文子串——Java版
  49. 【leetcode刷题】19.回文链表——Java版
  50. 【leetcode刷题】18.反转链表——Java版
  51. 【leetcode刷题】17.相交链表——Java&python版
  52. 【leetcode刷题】16.环形链表——Java版
  53. 【leetcode刷题】15.汉明距离——Java版
  54. 【leetcode刷题】14.找到所有数组中消失的数字——Java版
  55. 【leetcode刷题】13.比特位计数——Java版
  56. oracle控制用户权限命令
  57. 三年Java开发,继阿里,鲁班二期Java架构师
  58. Oracle必须要启动的服务
  59. 万字长文!深入剖析HashMap,Java基础笔试题大全带答案
  60. 一问Kafka就心慌?我却凭着这份,图灵学院vip课程百度云