> For the complete documentation index, see [llms.txt](https://php7.shujuwajue.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://php7.shujuwajue.com/php-biao-zhun-gui-fan-ji-kai-fa-ji-qiao/mian-xiang-dui-xiang-bian-cheng-de-ji-ben-yuan-ze.md).

# 面向对象编程的基本原则

1. **单一职责原则**：一个类，只需要做好一件事情．
2. **开放封闭原则**：一个类，应该是对扩展是开放的，但是对修改是封闭的；不应该使用修改增加功能，而是通过扩展来增加功能.
3. **依赖倒置原则**：一个类，不应该强依赖另外一个类．每个类对于另外一个类都是可替换的．
   1. 比如有A和B两个类，当A类依赖B类时，A类不能在其中直接调用B类，而是应该使用依赖注入的方式，通过注入将B类对象注入给A类，这样B类对于A类来说就是可以替换的.当新类C类实现了与B类实现了一致的接口类，这样就可以在B类和C类之间切换．
4. **配置化原则**：尽可能地使用配置，而不是硬编码．
5. **面向接口编程原则**：只需要关心接口，不需要关心实现．


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