摘要： High level modules should not depend upon low level modules.Both shoud depend upon abstractions.Abstractions should not depend upon details.Details sh 阅读全文

摘要： If for each object o1 of type S there is an object o2 of type T such that for all programs P defined in terms of T, the behavior of P is unchanged whe 阅读全文

摘要： 应该有且仅有一个原因引起类的变更. There should never be more than one reason for a class to change。 单一职责适用于接口,类,甚至是方法. 但对于类来说,往往又很难说. 因为受限于实际情况的多种因素影响,往往并不能保证类的单一职责. 阅读全文