在hibernate / jpa实体类中定义save方法是否是一个好习惯？

Question

I have a hibernate entity/model class as given below

class User{
  private Integer id,
  Private String name,
  private String description

  //getters and setters

   public void Save(this){
  }
}

Is it a good convention to define save method inside this class declaration along with setters and getters? Do we have any benefit of using like this such as avoiding duplicate records?

Answer 1

No, that is not a good convention. Usually you have a special layer called DAO (Data Access Object) that cares about saving/fetching/deleting... your entities. The Domain Models (ie your entities) represent only data, and there is the DAO layer that plays with them. With such a powerful specification as JPA you could merge your DAO layer with your Business Logic layer (EJB/Beans/CDI), but that could be the topic for another discussion. Of course you could have some validation things in your entity, or eg a method getLoggingString() that is not persisted, but returns a String version of the entity to be logged.

PS: the method that you wrote makes little sense with that signature: you need either a public User save() method that saves itself or you need a static public User save(User userToSave) .

Some references:

1. DAO
2. Should you have a separate DAO layer (ie not merged with your business layer)?