很多初学三层架构的用户，都对三层架构无从入手！而这些用户往往 会通过搜索引擎搜索，例如“最简单的三层架构例子”,等关键词， 就算用户找到这个实例，又会感觉不太明白，（心想有没有还可以再 简单的例子）！(Many beginners three tier architecture users, three layers of architecture can not start! And these users tend to Search engines, such as "t