What are VO, do, dto and Po

1、VO

        vo（view object） View objects

         For display layer , Its function is to put a specified page （ Or component ） All the data of , Generally, it is transmitted from the back end to the front end .

2、DTO

        DTO（data transfer object） Data transmission object

         Used for data transmission between presentation layer and logic layer .

3、DO

        DO（domain object）

         Tangible or intangible business entities abstracted from the real world .

4、PO

        po（persistent object）

         It forms a one-to-one correspondence with the data structure of the persistence layer . If the persistence layer is a relational database , that PO The attributes of and fields in the database correspond one by one .

5、VO and DTO The difference between

         The most essential difference between them is ：VO Represents the data that needs to be displayed ,DTO Represents the data that the service layer needs to receive and return .

give an example

         Take an operation of filling in a form as an example ：

1. The user fills out the form , The data of the form is matched as VO
2. The display layer puts VO Convert to what the service layer requires DTO, Pass it to the service layer
3. The service layer first bases on DTO Construct a DO, call DO Business method to complete specific business
4. The service layer will DO Convert to PO, Pass to persistence layer , The persistence layer completes the persistence operation