摘要：
Clients should not be forced to depend on methods that they do not use. 阅读全文
摘要：
a.High-level modules should not depend on low-level modules.Both should depend on abstractions.b.Abstractions should not depend on details.Detils should depend on abstractions. 阅读全文
摘要：
Subtypes must be substitutable for their base types. 阅读全文
摘要：
Software entities (class,modules,functions,etc.) should be open for extension,but closed for modification."Open for extension.":This means that the behavior of the module can be extended.As the requir... 阅读全文
摘要：
A class should have only one reason to change. 阅读全文
摘要：
Regidity--The system is hard to change because every change forces many other changes to other parts of the system. Fragility--Changes cause the system to break in places that have no concept... 阅读全文