POJO（Plain Ordinary Java Object） It's a simple object , And there are no rules to constrain . Sometimes take POJO To be used as a transfer object Java bean
DTO（Data Transfer Object） It's the data transfer object , Objects used solely for data transmission . Some projects are divided into InDto and OutDto , Input and output Dto .
PO（Persistant Object） It's a persistent object , It can be seen as mapping to tables in the database Java object . The simplest PO It is a record in a table corresponding to the database , Multiple records can be used PO Set . PO Does not contain business logic and data logic . It's a Entity Or say ModelEntity .
BO（Business Object） It's a business object , One that is often used , Related to the business , Each business may need a lot of PO （ Database table ） To form a , When you return to the front page or to the caller , We need to combine . BO That comes in handy , It's a right PO The combination of , It can also be PO , Only the starting point is to meet the service transmission object .
VO（Value Object） Value object , It's also a transport object .
DAO（Data Access Object） It's a data access object , It's usually the last layer to deal with the data layer , adopt DAO Identify the database , Finally, we return the data we want . Usually with our PO 、 BO Equal foundation type , Such as List 、Map And so on
Entity Is a persistent object associated with a database
JavaBean Is a persistent object associated with a database