PO: Persistant Object persistent object, can be seen as a Java object mapped in a database in the database. The simplest PO is a record in a table in a database, and multiple records can be used in PO. The PO should not contain any operations for the database.
Vo: Value Object Value Object. Data transfer between the business layers, and the PO is also only included in data. However, it should be an abstract business object, which can be corresponding to the table, or it may not, this is based on the needs of the business. Person feels the same DTO (data transfer object), passed on the web.
DAO: Data Access Object Data Access Objects, this object is used to access the database. Typically and PO is used in conjunction with the DAO, the operation method of various databases is included. Through its method, the Database is combined with PO.
BO: Business Object Business Object, Java object of package business logic, by calling the DAO method, combined with PO, VO for business operations;
Pojo: Plain ORDINARY JAVA Object Unregistered Java object, I personally think it and other things that are not one level, VO and PO should belong to it.
