如何将JPA映射类中的操作保存到数据库中时触发操作？

I want to have a function in one of my JPA annotated classes that is called every time the EntityManager saves them to the database (aka event listener). Is that possible? Preferably, I'd like to distinguish whether it is just about to be saved or has just been saved.I want to have a function in one of my JPA anno