The Object classification

1. Persistantobject (PO

A PO is a record in a table in the corresponding database. Multiple records can be used as a set of PO. The PO should not contain any operations on the database.

2.DO (DomainObject) DomainObject

Business entities, tangible or intangible, abstracted from the real world.

3.TO(TransferObject) : data TransferObject

Objects transferred between different applications

4.DTO (DataTransferObject) DataTransferObject

This concept comes from the J2EE design pattern. The original purpose is to provide coarse-grained data entities for the distributed application of EJB, so as to reduce the number of distributed calls, thereby improving the performance of distributed calls and reducing network load. But in this context, it generally refers to the data transfer objects between the display layer and the service layer.

5. VO (valueobject) value object

It is commonly used for data transfer between business layers and, like PO, contains only data. But it should be an abstract business object, which may or may not correspond to a table, depending on the needs of the business. Created with the new keyword and collected by GC. Viewobject: a Viewobject; Accept the data from the page, encapsulate the object that the business has completed, encapsulate the data that the page will use

6.BO(businessobject) businessobject

From a business model perspective, see domain objects in the UML Component Domain model. Encapsulate the business logic of Java objects, by calling DAO method, combined with PO,VO business operations. Businessobject: the main purpose of a businessobject is to encapsulate business logic as an object. This object can contain one or more other objects. A resume, for example, has educational experience, work experience, social connections and so on. We can assign educational experience to one PO, work experience to one PO, and social connections to one PO. Create a BO object corresponding to the resume to process the resume, and each BO contains these pos. This allows us to process the business logic against the BO.

7.POJO(plainordinaryjavaobject) simple random Java objects

Java objects in the traditional sense. That is, in some Object/RelationMapping tools, persisentobject that can maintain database table records is a pure Java Object that conforms to the JavaBean specification, without adding other attributes and methods. My understanding is a basic javaBean, just property fields and setter and getter methods! . POJO is a general term for DO/DTO/BO/VO.

DAO(dataaccessobject) dataaccessobject

Is a standard J2EE design pattern for Sun, and one of the interfaces in this pattern is DAO, which negates persistence layer operations. Provides interfaces to the business layer. This object is used to access the database. Often used in conjunction with a PO, daOs contain operations on various databases. Through its method, combined with PO to carry out relevant operations on the database. Sandwiched between business logic and database resources. Cooperate with VO to provide CRUD operation of database.