Java 之 23 种设计模式解析——创建模式、简单工厂模式

朱雀 2022-05-17 02:37 188阅读 0赞

# **三、Java 的 23 中设计模式** #

**A****、创建模式**

从这一块开始，我们详细介绍 Java 中 23 种设计模式的概念，应用场景等情况，并结合他们的特点及设计模式的原则进行分析。

首先，简单工厂模式不属于 23 中涉及模式，简单工厂一般分为：普通简单工厂、多方法简单工厂、静态方法简单工厂。

### **0、简单工厂模式** ###

简单工厂模式模式分为三种：

***01******、普通***

就是建立一个工厂类，对实现了同一接口的一些类进行实例的创建。首先看下关系图：

![70][]

举例如下：（我们举一个发送邮件和短信的例子） 首先，创建二者的共同接口：

<table style="margin-left:5.75pt;width:470.75pt;"> 
 <tbody> 
 <tr> 
 <td colspan="2" style="background-color:#f8f8f8;width:470.75pt;"> [java] <a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">view plain</a><a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">copy</a> </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:456.1pt;"> 1. public interface Sender { </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 2. public void&nbsp;Send(); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 3.&nbsp;} </td> 
 </tr> 
 </tbody> 
</table>

其次，创建实现类：

<table style="margin-left:55.15pt;width:470.75pt;"> 
 <tbody> 
 <tr> 
 <td colspan="2" style="background-color:#f8f8f8;width:470.75pt;"> [java] <a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">view plain</a><a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">copy</a> </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:456.1pt;"> 1. public class MailSender implements Sender { </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 2. @Override </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 3. public void Send()&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 4. System.out.println("this is&nbsp;mailsender!"); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 5. } </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 6.&nbsp;} </td> 
 </tr> 
 <tr> 
 <td colspan="2" style="background-color:#f8f8f8;width:470.75pt;"> [java] <a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">view plain</a><a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">copy</a> </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:456.1pt;"> 1. public class SmsSender implements Sender { </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 2. </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 3. @Override </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 4. public void Send()&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 5. System.out.println("this is sms&nbsp;sender!"); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 6. } </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 7.&nbsp;} </td> 
 </tr> 
 </tbody> 
</table>

最后，建工厂类：

<table style="margin-left:55.15pt;width:470.75pt;"> 
 <tbody> 
 <tr> 
 <td colspan="2" style="background-color:#f8f8f8;width:470.75pt;"> [java] <a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">view plain</a><a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">copy</a> </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:456.1pt;"> 1. public class SendFactory { </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 2. </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 3. public Sender produce(String type)&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 4. if ("mail".equals(type))&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 5. return new&nbsp;MailSender(); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 6. } else if ("sms".equals(type))&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 7. return new&nbsp;SmsSender(); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 8. } else&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 9. System.out.println("请输入正确的类型!"); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 10. return&nbsp;null; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 11. } </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 12. } </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 13. } </td> 
 </tr> 
 </tbody> 
</table>

我们来测试下：

<table style="margin-left:70.6pt;width:456.1pt;"> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 1. public class FactoryTest { </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 2. </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 3. public static void main(String[] args)&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 4. SendFactory factory = new&nbsp;SendFactory(); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 5. Sender sender = factory.produce("sms"); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 6. sender.Send(); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:456.1pt;"> 7. } </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:456.1pt;"> 8.&nbsp;} </td> 
 </tr> 
 </tbody> 
</table>

输出：this is sms sender!

***02******、多个方法***

是对普通工厂方法模式的改进，在普通工厂方法模式中，如果传递的字符串出错，则不能正确创建对象， 而多个工厂方法模式是提供多个工厂方法，分别创建对象。关系图：

![70 1][]

将上面的代码做下修改，改动下 SendFactory 类就行，如下：

测试类如下：

输出：this is mailsender!

***03******、多个静态方法***

将上面的多个工厂方法模式里的方法置为静态的，不需要创建实例，直接调用即可。

<table style="margin-left:55.15pt;width:470.7pt;"> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 1. public class SendFactory { </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 2. </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 3. public static Sender&nbsp;produceMail(){ </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 4. return new&nbsp;MailSender(); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:16.45pt;"> 5. </td> 
 <td style="vertical-align:top;width:16.35pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:423.25pt;"> } </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 6. </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 7. public static Sender&nbsp;produceSms(){ </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 8. return new&nbsp;SmsSender(); </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:16.45pt;"> 9. </td> 
 <td style="vertical-align:top;width:16.35pt;"> &nbsp; </td> 
 <td style="vertical-align:top;width:423.25pt;"> } </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 10. } </td> 
 </tr> 
 <tr> 
 <td colspan="4" style="background-color:#f8f8f8;width:470.7pt;"> [java] <a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">view plain</a><a href="http://blog.csdn.net/zhangerqing/article/details/8194653" rel="nofollow">copy</a> </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:14.65pt;"> &nbsp; </td> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 1. public class FactoryTest { </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 2. </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 3. public static void main(String[] args)&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="background-color:#f8f8f8;width:456.05pt;"> 4. Sender sender = SendFactory.produceMail(); </td> 
 </tr> 
 <tr> 
 <td colspan="3" style="vertical-align:top;width:456.05pt;"> 5. sender.Send(); </td> 
 </tr> 
 <tr> 
 <td style="background-color:#f8f8f8;width:16.45pt;"> 6. </td> 
 <td style="background-color:#f8f8f8;width:16.35pt;"> &nbsp; </td> 
 <td style="background-color:#f8f8f8;width:423.25pt;"> } </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:16.45pt;"> 7. </td> 
 <td style="vertical-align:top;width:16.35pt;"> } </td> 
 <td style="vertical-align:top;width:423.25pt;"> &nbsp; </td> 
 </tr> 
 </tbody> 
</table>

输出：this is mailsender!

总体来说，工厂模式适合：凡是出现了大量的产品需要创建，并且具有共同的接口时，可以通过工厂方法模式进行创建。在以上的三种模式中，第一种如果传入的字符串有误，不能正确创建对象，第三种相对于第二种，不需要实例化工厂类，所以，大多数情况下，我们会选用第三种——静态工厂方法模式。

## 目录：（点击进入相应页面） ##

# [概述、六大原则][Link 1] #

# 一、[创建模式][Link 2] #

**[0、][Link 2][简单工厂模式][Link 2]**

**[1.工厂方法模式（Factory Method）][1._Factory Method]**

**[2、抽象工厂模式][2]**

**[3、单例模式（Singleton）][3_Singleton]**

**[4、建造者模式（Builder）][4_Builder]**

**[5、原型模式（Prototype）][4_Builder]**

# **二、[结构模式（7种）][7]** #

**[6、适配器模式][7]**

**[7、装饰模式（Decorator）][7_Decorator]**

**[8、代理模式（Proxy）][8_Proxy]**

**[9、外观模式（Facade）][9_Facade]**

**[10、桥接模式（Bridge）][10_Bridge]**

**[11、组合模式（Composite][11_Composite][）][11_Composite]**

**[12、享元模式（Flyweight）][12_Flyweight]**

# **三、[关系模式（11种）][11]** #

**[13、策略模式（strategy）][11]**

**[14、模板方法模式（Template Method）][14_Template Method]**

**[15、观察者模式（Observer）][15_Observer]**

**[16、迭代子模式（Iterator）][16_Iterator]**

**[17、责任链模式（Chain of Responsibility）][17_Chain of Responsibility]**

**[18、命令模式（Command）][18_Command]**

**[19、备忘录模式（Memento][19_Memento]**

**[20、状态模式（State）][20_State]**

**[21、访问者模式（Visitor）][21_Visitor]**

**[22、中介者模式（Mediator）][22_Mediator]**

**[23、解释器模式（Interpreter）][23_Interpreter]**

[70]: /images/20220517/d7a84fb920d14c3bbff7f8131e6b209c.png
[70 1]: /images/20220517/e5fd8095f3cb4dc686893cd51fde9349.png
[Link 1]: https://blog.csdn.net/bifuguo/article/details/81431513
[Link 2]: https://blog.csdn.net/bifuguo/article/details/81432164
[1._Factory Method]: https://blog.csdn.net/bifuguo/article/details/81432186
[2]: https://blog.csdn.net/bifuguo/article/details/81432269
[3_Singleton]: https://blog.csdn.net/bifuguo/article/details/81432392
[4_Builder]: https://blog.csdn.net/bifuguo/article/details/81432437
[7]: https://blog.csdn.net/bifuguo/article/details/81432564
[7_Decorator]: https://blog.csdn.net/bifuguo/article/details/81432726
[8_Proxy]: https://blog.csdn.net/bifuguo/article/details/81432762
[9_Facade]: https://blog.csdn.net/bifuguo/article/details/81432774
[10_Bridge]: https://blog.csdn.net/bifuguo/article/details/81432829
[11_Composite]: https://blog.csdn.net/bifuguo/article/details/81432877
[12_Flyweight]: https://blog.csdn.net/bifuguo/article/details/81432901
[11]: https://blog.csdn.net/bifuguo/article/details/81432950
[14_Template Method]: https://blog.csdn.net/bifuguo/article/details/81432992
[15_Observer]: https://blog.csdn.net/bifuguo/article/details/81433043
[16_Iterator]: https://blog.csdn.net/bifuguo/article/details/81433082
[17_Chain of Responsibility]: https://blog.csdn.net/bifuguo/article/details/81433127
[18_Command]: https://blog.csdn.net/bifuguo/article/details/81433162
[19_Memento]: https://blog.csdn.net/bifuguo/article/details/81434127
[20_State]: https://blog.csdn.net/bifuguo/article/details/81434167
[21_Visitor]: https://blog.csdn.net/bifuguo/article/details/81434187
[22_Mediator]: https://blog.csdn.net/bifuguo/article/details/81434209
[23_Interpreter]: https://blog.csdn.net/bifuguo/article/details/81434237