一、定义里氏置换原则（Liskov Substitution Principle），简称LSPFunctions that use pointers or references to base classes must be able to use objects of derived classes without knowing it.所有引用基类的地方必须能够透明的使用其子类

一、定义单一职责原则（Single Responsibility Principle），简称SRP。There should never be more than one reason for a class to change.应该有且仅有一个原因引起类的变更。单一职责的意义：1、降低类的复杂性，实现什么样的职责都有清晰的定义2、提高可读性

1、定义In object-oriented programming, the dependency inversion principle refers to a specific form of decoupling software modules. When following this principle, the conventional dependency relation