The system explains, dao,entity,servlet,action each have what thing-java/web develop

DAO is mainly a number of interfaces, which define some of the methods used to delete and change the name

Daoimpl  is the concrete implementation of DAO

Service Ibid, also some interfaces, mainly used to invoke the DAO layer of some methods, so the method defined here generally defines the parameters;

Serviceimp a specific implementation of the service, here are some ways to invoke DAO

The servlet invokes the service to invoke its method, doing some operations

JSP view display and input data





The DAO layer is the database layer's primary responsibility for establishing database connections to execute database commands and return results

Entity is primarily a physical layer where entities are placed  

A servlet is a technical action that is a small part of the servlet! We mainly use Servlets to intercept requests during web development, and do nothing else to return requests!

Note that layering must be clear in software development! To tell you a classic pattern MVC three-tier architecture

The M model layer is primarily responsible for your entity class!
The C control layer is primarily responsible for the control of business processes
The V (view) view layer is primarily responsible for the display of the page

The system explains, dao,entity,servlet,action each have what thing-java/web develop