Several Java objects (PO, Vo, Dao, Bo, pojo)

Several Java objects (PO, Vo, Dao, Bo, pojo)
I. Po: persistence object of persistant object. It can be regarded as a Java object mapped to a table in the database. The simplest Po is to correspond to a record in a table in the database. A set of PO can be used for multiple records. The PO should not contain any operations on the database.

Ii. VO: Value Object value object. It is usually used for data transmission between business layers. Like Po, it only contains data. However, it should be an abstract business object, which can correspond to a table or not. This is based on the business needs. I personally think it is the same as DTO (data transmission object) and transmitted on the web.

3. Dao: Data Access Object: the data access object used to access the database. It is usually used in combination with Po. Dao contains various database operation methods. It combines Po with other methods to perform database operations.

4. Bo: Business Object business object. It encapsulates Java objects of business logic and performs business operations by calling Dao and combining Po and VO.

5. pojo: plain ordinary Java object is a Java object with no rules. I personally think it and others are not at the same level. Vo and PO should both belong to it.