Core j2EE Pattern, BO, TO, VO,

 

BusinessObject

 

The BusinessObject represents a role in this pattern that can be fulfilled by a session bean, an entity bean, or a Data Access Object (DAO). The BusinessObject is responsible for creating the Transfer Object and returning it to the client upon request. The BusinessObject may also receive data from the client in the form of a Transfer Object and use that data to perform an update.

 

TransferObject

 

The TransferObject is an arbitrary serializable Java object referred to as a Transfer Object. A Transfer Object class may provide a constructor that accepts all the required attributes to create the Transfer Object. The constructor may accept all entity bean attribute values that the Transfer Object is designed to hold. Typically, the members in the Transfer Object are defined as public, thus eliminating the need for get and set methods. If some protection is necessary, then the members could be defined as protected or private, and methods are provided to get the values. By offering no methods to set the values, a Transfer Object is protected from modification after its creation. If only a few members are allowed to be modified to facilitate updates, then methods to set the values can be provided. Thus, the Transfer Object creation varies depending on an application's requirements. It is a design choice as to whether the Transfer Object's attributes are private and accessed via getters and setters, or all the attributes are made public.

 

 

 

ValueBean

 

A value bean is another name for a helper that is responsible for holding intermediate model state for use by a view. 

这就是传说中的 View Object。