面向对象设计的SOLID原则

秒速五厘米 2021-09-10 19:42 365阅读 0赞

S.O.L.I.D是面向对象设计和编程(OOD&OOP)中几个重要编码原则(Programming Priciple)的首字母缩写。

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   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <strong>SRP</strong></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <a href="http://www.objectmentor.com/resources/articles/srp.pdf" style="color:rgb(70,70,70)" rel="nofollow">The Single Responsibility Principle&nbsp;</a></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> 单一责任原则</td> 
  </tr> 
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   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <strong>OCP</strong></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <a href="http://www.objectmentor.com/resources/articles/ocp.pdf" style="color:rgb(70,70,70)" rel="nofollow">The Open Closed Principle</a>&nbsp;</td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> 开放封闭原则</td> 
  </tr> 
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   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <strong>LSP</strong></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <a href="http://www.objectmentor.com/resources/articles/lsp.pdf" style="color:rgb(70,70,70)" rel="nofollow">The Liskov Substitution Principle</a></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> 里氏替换原则</td> 
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   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <strong>DIP</strong></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <a href="http://www.objectmentor.com/resources/articles/dip.pdf" style="color:rgb(70,70,70)" rel="nofollow">The Dependency Inversion Principle</a></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> 依赖倒置原则</td> 
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   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <strong>ISP</strong></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> <a href="http://www.objectmentor.com/resources/articles/isp.pdf" style="color:rgb(70,70,70)" rel="nofollow">The Interface Segregation Principle</a></td> 
   <td style="border:1px solid silver; border-collapse:collapse; padding:3px"> 接口分离原则</td> 
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</table>

[Steve Smith][]在5月份的微软TechED 2009上有个[SOLIDify Your ASP.NET MVC][]的讲座, [derick.bailey][]的[SOLID Development Principles – In Motivational Pictures][SOLID Development Principles _ In Motivational Pictures]很好的解释了SOLID原则。

**单一责任原则：**   
当需要修改某个类的时候原因有且只有一个（THERE SHOULD NEVER BE MORE THAN ONE REASON FOR A CLASS TO CHANGE）。换句话说就是让一个类只做一种类型责任，当这个类需要承当其他类型的责任的时候，就需要分解这个类。   
 [![SingleResponsibilityPrinciple2\_71060858][SingleResponsibilityPrinciple2_71060858]][SingleResponsibilityPrinciple2_71060858_SingleResponsibilityPrinciple2_71060858]

**开放封闭原则**   
软件实体应该是可扩展，而不可修改的。也就是说，对扩展是开放的，而对修改是封闭的。这个原则是诸多面向对象编程原则中最抽象、最难理解的一个。

[![OpenClosedPrinciple2\_2C596E17][OpenClosedPrinciple2_2C596E17]][OpenClosedPrinciple2_2C596E17_OpenClosedPrinciple2_2C596E17]

**里氏替换原则**   
当一个子类的实例应该能够替换任何其超类的实例时，它们之间才具有is-A关系   
[![LiskovSubtitutionPrinciple\_52BB5162][LiskovSubtitutionPrinciple_52BB5162]][LiskovSubtitutionPrinciple_52BB5162_LiskovSubtitutionPrinciple_52BB5162]    
**依赖倒置原则**  
1. 高层模块不应该依赖于低层模块，二者都应该依赖于抽象   
2. 抽象不应该依赖于细节，细节应该依赖于抽象   
[![DependencyInversionPrinciple\_0278F9E2][DependencyInversionPrinciple_0278F9E2]][DependencyInversionPrinciple_0278F9E2_DependencyInversionPrinciple_0278F9E2]

**接口分离原则**   
不能强迫用户去依赖那些他们不使用的接口。换句话说，使用多个专门的接口比使用单一的总接口总要好。

[![InterfaceSegregationPrinciple\_60216468][InterfaceSegregationPrinciple_60216468]][InterfaceSegregationPrinciple_60216468_InterfaceSegregationPrinciple_60216468]

这几条原则是非常基础而且重要的面向对象设计原则。正是由于这些原则的基础性，理解、融汇贯通这些原则需要不少的经验和知识的积累。上述的图片很好的注释了这几条原则。

[Steve Smith]: http://stevesmithblog.com/
[SOLIDify Your ASP.NET MVC]: http://stevesmithblog.com/blog/teched-2009-session-aftermath/
[derick.bailey]: http://www.lostechies.com/members/derick.bailey/default.aspx
[SOLID Development Principles _ In Motivational Pictures]: http://www.lostechies.com/blogs/derickbailey/archive/2009/02/11/solid-development-principles-in-motivational-pictures.aspx
[SingleResponsibilityPrinciple2_71060858]: http://images.cnblogs.com/cnblogs_com/shanyou/WindowsLiveWriter/SOLID_6402/SingleResponsibilityPrinciple2_71060858_thumb.jpg
[SingleResponsibilityPrinciple2_71060858_SingleResponsibilityPrinciple2_71060858]: /images/20210726/6e5e8b8b4f1d4a6db3f241641ea215c7.png
[OpenClosedPrinciple2_2C596E17]: http://images.cnblogs.com/cnblogs_com/shanyou/WindowsLiveWriter/SOLID_6402/OpenClosedPrinciple2_2C596E17_thumb.jpg
[OpenClosedPrinciple2_2C596E17_OpenClosedPrinciple2_2C596E17]: /images/20210726/ea1dce71663c49c3a221b5ab8a5de095.png
[LiskovSubtitutionPrinciple_52BB5162]: http://images.cnblogs.com/cnblogs_com/shanyou/WindowsLiveWriter/SOLID_6402/LiskovSubtitutionPrinciple_52BB5162_thumb.jpg
[LiskovSubtitutionPrinciple_52BB5162_LiskovSubtitutionPrinciple_52BB5162]: /images/20210726/1cdefdafa43d48fca98ba70992ff917f.png
[DependencyInversionPrinciple_0278F9E2]: http://images.cnblogs.com/cnblogs_com/shanyou/WindowsLiveWriter/SOLID_6402/DependencyInversionPrinciple_0278F9E2_thumb.jpg
[DependencyInversionPrinciple_0278F9E2_DependencyInversionPrinciple_0278F9E2]: /images/20210726/8d45dbed930c4210ab32adbb16dc18c5.png
[InterfaceSegregationPrinciple_60216468]: http://images.cnblogs.com/cnblogs_com/shanyou/WindowsLiveWriter/SOLID_6402/InterfaceSegregationPrinciple_60216468_thumb.jpg
[InterfaceSegregationPrinciple_60216468_InterfaceSegregationPrinciple_60216468]: /images/20210726/5c39d09f590a455297151dc4ae973ed5.png