问题
What is the difference between
- A simple fields-accesors-mutators class
- A rich-modeled class
What constitutes rich modeling in business-domain classes?
回答1:
"Rich" as used here implies "rich behavior" (as opposed to state).
There is technical behavior and domain behavior. Accessors and mutators are technical; they lack the "why" which defines business interest.
Domain objects represent the "why" and encapsulate the "how". Actually, all objects do that; domain objects do it specifically for business value.
Let's say you, as an employee domain object, have to request a day off of work. You have 2 options:
- Tell your manager and he marks the schedule.
- Ask your manager for the schedule and mark it.
Model 1 is rich. The "why" (vacation time) encapsulates the "how" (marking the schedule).
Model 2 relegates the manager to a simple property bag and leaks the scheduling abstraction.
回答2:
When your business logic is encapsulated in your business objects. In other words, you have a Business Objects (Domain Model) layer, without the need for a separate Business Logic layer.
来源：https://stackoverflow.com/questions/311608/what-constitutes-a-rich-domain-model-in-a-pojo-poco