对c#的经典实例petshop进行了抽取，将复杂的缓存体系去掉，只保留业务、数据这些逻辑体系，以供初学者进行研究、学习。-The classic example of c# petshop were drawn, complex caching system removed, leaving only the business logic of the data in these systems, for beginners to study and learn.