Summary of differences between JAVA objects POJO, DAO, DTO, PO, BO, VO

position	Object name	alias	effect
Global	Plain Ordinary Java Object	POJO	Ordinary Java object
Data access layer	Data Access Object	DAO	Data access object, database-oriented interface, located at the bottom
Data transfer layer	Data Transfer Object	DTO	Data transfer object, used for table structure hiding, field reduction, etc.
Persistence layer	Persistent Object	PO	Persistence layer objects, one-to-one correspondence with database fields
Business Layer	Business Object	BO	Business object, can encapsulate multiple PO
Presentation layer	Value Object	VO	Value object, used for business layer data transfer