Java's (Po,vo,to,bo,dao,pojo) explanation
PO (Persistant object) Persistent object
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.
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 the business object that can correspond to the table, or not, depending on the needs of the business. Personally feel the same DTO (data transfer object) that is passed on the web.
to (Transfer object), data transfer object
Objects that are transferred between different tie (relationships) in the application
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.
POJO (Plain ordinary Java object) simple, rule-free Java objects
Java objects that are purely traditional in 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!.
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, provide database crud operations ...
O/R Mapper object/relationship Mapping
After defining all the mapping, this O/R mapper can help us do a lot of work. With these mappings, this O/R mapper can generate all the SQL statements about the object save, Delete, read, and we no longer need to write so many lines of DAL code.
Entity model (solid mode)
DAL (data access Layer)
Idal (interface layer)
Dalfactory (class factory)
BLL (business logic Layer)
BOF business Object Framework service objects Frame
SOA Service Orient Architecture Services-oriented design
EMF Eclipse Model Framework Eclipse Modeling Framework
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PO: Full name is
Persistant Object Persistent Objects
The most vivid understanding is that a PO is a record in the database.
The advantage is that a record can be processed as an object and can be easily converted to other objects.
BO: The full name is
Business object: Operational objects
The main role 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.
VO:
Value Object Value objects
ViewObject Presentation Layer Objects
The data object that the main interface displays. For a Web page, or an interface for SWT and swing, use a Vo object to correspond to the value of the entire interface.
Dto:
Data Transfer Object Data transfer objects
It is mainly used for remote calls, etc. where large quantities of objects need to be transferred.
For example, if we have 100 fields in a table, then the corresponding PO has 100 attributes.
But we just show 10 fields on the interface,
The client uses the Web service to get the data, and there is no need to pass the entire PO object to the client.
At this point we can pass the result to the client with a DTO with only these 10 attributes, and this will not expose the service-side table structure. After the client is reached, if the interface is displayed with this object, then its identity will be converted to VO.
Pojo:
Plain ordinary Java object simple Java objects
Personal feeling Pojo is the most common and changeable object, is an intermediate object, is also our most often dealing with objects.
A Pojo is a PO after persistence
It is the DTO that passes and passes directly through it.
Directly used to correspond to the presentation layer is VO
DAO:
Data Access Object Information
This everyone is most familiar with, and the above several o the biggest difference, basic without the possibility and necessity of mutual transformation.
Primarily used to encapsulate access to a database. It can be pojo to the PO, with PO assembled VO, DTO
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The Po:persistant object is persisted as a Java object that is 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.
The Vo:value object value. 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 the business object that can correspond to the table, or not, depending on the needs of the business. Personally feel the same DTO (data transfer object) that is passed on the web.
Dao:data Access object that 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.
Bo:business object, which encapsulates the Java object of the business logic, invokes the DAO method and combines po,vo for business operations;
Pojo:plain ordinary Java object Simple, non-regular Java objects, I personally think it and other not a level of things, Vo and Po should belong to it.
VO: Value object, view object
PO: Persistent Object
QO: Querying objects
DAO: Data Access Object
DTO: Data Transfer Object
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The actionform in struts is a VO;
The entity Bean in Hibernate is a PO, also called Pojo;
The criteria in hibernate is equivalent to a qo;
When using hibernate, we define some methods of querying, which are written in the interface and can have different implementation classes. And this interface can be said to be a DAO.
Personally think Qo and DTOs are similar.
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Po or bo, the closest layer to the database, is an ORM O, basically a database field corresponding to a property in Bo, for synchronization and security considerations, it is best to give DAO or service calls, rather than using Packcode,backingbean, or Bo tune.
DAO, the data access layer, the object in the Vo,backingbean can be put into ....
DTOs, seldom used, are basically put into DAO, but play a role in transition.
QO, is to put some with persistent query operations with the statement into the.
The basic elements and methods used in the VO,V layer are placed therein. If you want to call Bo, do the Bo conversion vo,vo convert Bo operation. Vo's advantage is that its page element attributes more than Bo, can play a very good role ....
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It's not right upstairs, PO is a persistent object. Bo=business object-business object.
The PO can be strictly corresponding to the database table, and a single PO is mapped to a table.
Bo is the business logic processing object, my understanding is that it is filled with business logic processing, in the business logic of complex applications to be useful.
Vo:value Object value objects, view object views
PO: Persistent Object
QO: Querying objects
DAO: Data Access Object--also DAO mode
DTO: Data Transfer Object-also DTO mode
Java Professional Terminology