The concept of PO, do, to, DTO, VO, BO, POJO, DAO in Java

1.PO (Persistant object) Persistent objects

?? The concept that occurs at the O/R mapping, without the O/R mapping, does not exist. Usually the corresponding data model (database), itself also has some business logic processing. Can be seen as a Java object mapped to a table in the database. The simplest PO is a record in a table in the corresponding database, and multiple records can be used with a collection of PO. The PO should not contain any operations on the database.

2.DO (domain object) domain objects

?? is a tangible or intangible business entity that is abstracted from the real world.

3.TO (Transfer object), data transfer objects

?? Objects that are transferred between different applications

4.DTO (Data Transfer object) data transfer objects

?? This concept derives from the design pattern of the Java EE, which was originally designed to provide coarse-grained data entities to the distributed application of EJBS to reduce the number of distributed calls, thereby improving the performance of distributed calls and reducing network load, but here I refer to the data transfer objects between the presentation layer and the service layer.

5.VO (Value object) value objects

?? Typically used for data transfer between business tiers, as is the case with PO, which contains only data. But it should be abstracted out of business objects that can correspond to tables, or not, depending on the needs of the business. Created with the new keyword, collected by GC.

6.BO (business object) service object

?? From the business model perspective, see the domain objects in the UML component Domain model. A Java object that encapsulates the business logic, by invoking the DAO method and combining PO,VO for business operations. Business object: The primary role of the operational objects is to encapsulate the business logic as an object. This object can include one or more other objects. such as a resume, education experience, work experience, social relations and so on. We can have an education experience corresponding to a PO, work experience corresponding to a PO, social relations corresponding to a PO. Create a CV-based Bo object to process resumes, each Bo containing these PO. When we handle business logic like this, we can deal with BO.

7.POJO (Plain ordinary Java object) simple, rule-free Java objects

?? Java object of traditional meaning. In some object/relation Mapping tools, the Persisent object that maintains database table records is a pure Java object that conforms to the Java Bean specification and does not add other properties and methods. My understanding is the most basic Java Bean, only attribute fields and setter and getter Method!.

?? Pojo is a general term for DO/DTO/BO/VO.

8.DAO (data Access object) Access objects

?? is a sun's standard Java EE design pattern, which has an interface that is DAO, which has negative persistence layer operations. Provides interfaces for the business layer. This object is used to access the database. Usually used in conjunction with PO, DAO contains various methods of operation of the database. Through its method, combine the PO to carry on the related operation to the database. Sandwiched between business logic and database resources. With VO, provides a CRUD operation of the database.

The concept of PO, do, to, DTO, VO, BO, POJO, DAO in Java