Recently heard in class VO, I do not know what it means
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First, a brief description follows:
O / R Mapping is an abbreviation Object Relational Mapping (object-relational mapping) of. Simply put, the object and relational databases binding, object-relational data to represent.
Java WEB three-tier architecture we need more skilled use
VO: value of the object (Value Object)
Create a new keyword, there is typically recovered GC for data transfer between the service layer, generally abstract business objects, and data may correspond to the table, or may not. In the web layer, corresponding to a web page or interface swt, a value corresponding to a VO interface with objects.
PO: persistent objects (Persistant Object)
Field attribute correspondence table in the database and can be viewed as a java object map to tables in the database. Generated by the database insert, delete from the database delete. It is closely related to their life cycle and the database, but the PO should not contain any operations on the database.
Java files which are generally database table attributes and corresponding fields get, set method
BO: business objects (business object)
The main role of the business logic is encapsulated into an object. This object can comprise one or more other objects. For example, a curriculum vitae, educational experience, internship experience, winning conditions, etc., to establish a correspondence BO object processing resumes resume, each of these BO contains PO, so that when business logic processing, we can be processed for BO.
DTO: Data transfer object (Data Transfer Object) mode while DTO
Mainly used for local transport objects requires a lot of long-distance calls and so on. For example, we have 100 fields in a table, then the corresponding PO brother have 100 properties. 10 but as long as the display fields on our interface, with the WEB service client to retrieve the data, there is no need to pass the entire client objects PO. This is what we can use this DTO only 10 properties to deliver results to the client, so it will not expose the server table structure. After reaching the client, if this object to display the corresponding interface, so this time it's turned on the identity of the VO
DAO: Data Access Objects (Data Access Object) while the DAO pattern
Mainly used to encapsulate access to the database, comprising the method of operating the various databases, the database provides CRUD operations. By durable it can POJO into PO, PO assembled with DTO, VO
POJO: simple Java objects (Plain Ordinary Java Object)
POJO is the most common target the most variable, is an intermediate object, we also deal with the most common objects.
After a POJO persistence is PO
It is transmitted directly by the transfer process is DTO
Layer is directly used to identify the corresponding VO