At present, the development of Java-based web applications is divided into 4 layers: representing layers, business layers, persistence layers, and DB layers.
(1) Representation
The view techniques used in the indication layer are mainly:
l JSP Taglibs (such as JSTL or some frames such as webwork2 tags)
l template frame (such as Veloctiy, FreeMaker)
(2) Business layer
The business layer can be divided into business logic layers and intermediate service layers. Business logic layer controls business processes, implementation technology: WebWork2, Struts, etc. The intermediate service layer provides a server framework. The current framework is based on Apache's Avalon. The compatible framework has Keel, SPICO, IVORY, etc., which changes on this basis Spring, Pico, etc.
(3) Hirus
The persistence layer provides a mapping (ORM) of Java objects to relational data, and technology has Hibernate, Ibatis, JDO, etc.
(4) DB layer
The DB layer uses the DAO (Data Access Object) to provide access to the underlying data storage, and the technology has Ibatis, Jingdao, etc.
