What is MVC:
Mvc is a design pattern
mvc:Model (model) view (view) Controller (controller)
divide and conquer
In earlier years:
Users directly access the control layer, and the control layer can directly operate the database;
servlet--CRUP-->数据库
弊端:程序十分臃肿,不利于维护
servlet的代码中:处理请求,响应,试图跳转,处理JDBC,处理业务代码,处理逻辑代码
MVC:
Model
- Business processing: business logic (Service)
- Data persistence layer: CRUD (Dao)
View
- display data
- Provide a link to initiate a Servlet request (a, form, img...)
Controller (servlet)
- Receive user's request: (req: request parameters, Session information...)
- Hand over the corresponding code to the business layer
- Control view jump
登录--->接收用户的登录请求--->处理用户的请求(获取用户登录的参数,username,password)--->交给业务层处理登录业务(判断用户名密码是否正确:事务) --->Dao层查询用户名和密码是否正确--->数据库