VO: value object, view object Po: Persistent Object Qo: query object Dao: Data Access Object DTO: Data Transmission

The actionform in struts is a Vo;
The Entity Bean in Hibernate is a po, also called pojo;
The criteria in Hibernate is equivalent to a Qo;
When using hibernate, we will define some query methods. These methods can be written in interfaces and have different implementation classes.
This interface can be said to be a Dao.
I personally think that Qo is similar to DTO.

Po is also called Bo. The closest layer to the database is the o in the orm. It is basically an attribute corresponding to the database field in the Bo. For the sake of synchronization and security, it is best to only call Dao or service, instead of using packcode, backingbean, Or Bo.
Dao, data access layer, put objects in vo and backingbean ....
DTO is rarely used. It is basically put into Dao, but serves as a transitional function.
Qo puts some query operations and statements with durability ..
Basic elements and methods used in vo and V layers are included. If you want to call Bo, you need to convert Bo to Vo and VO to Bo. The advantage of VO is that its page has more element attributes than Bo, which can play a very good role .... Po is a persistent object. BO = Business Object-business object.
A po can correspond to a database table strictly, and a table is mapped to a po.
Bo is the object of business logic processing. My understanding is that it is full of business logic processing and is useful in complicated business logic applications.
VO: value object Value Object and view object
Po: Persistent Object
Qo: query object
Dao: Data Access Object-there is also the DAO mode
Dto: Data Transmission object-also has the DTO Mode

Vo-doesn't know how to translate. It is generally used to represent the form, objects in the form. What the user sees.

Po-Persistent Object indicates the database entity. Dao-defines the object for Po operations, and implements some po operations, such as add, delete, and update.