服务类中的jpa继承和代码重用

Question

I have a parent entity, Person, and two children entities : Caller and Employee. The two children share a lot of fields so i implemented JPA inheritance with single table strategy and discriminator column.So far so good. In order to handle these objects i have some Service classes that handle database operations where i have methods like : getCallerById(); or getEmployeesByFirstName(). Also the save() methods are in these service classes. The problem is that when i want to save an employee or an caller i got a lot of duplicate code (for all the shared properties), so in order to prevent this i created a 3rd service: PersonService() in order to handle the common functionality. But now i do not know how to use this service in order to reuse as much code as i can. Maybe in the PersonService() to have something like

public Boolean save(Person p){
    if (p instanceOf Caller){
       Caller c = new Caller();
       c.setCallerSpecificProperty("XXX");
    }

    if (p instanceOf Employee){
      Employee c = new Employee()
      c.setEmployeeSpecificProperty("YYY");
    }

    c.setOtherCommonParameter("ccc");
   //............
}

or how do you advise me to handle this problem??? Thanks

Answer 1

if your problem is just to set the 100 commonProperties of Person, you can add helper method, say

 protected Person setCommonProperties(Person p){
p.setFoo(foo);
p.setBar(bar);
...
p.setWhatever(blahblah);

return p;
}

in your parentService( PersonService in your case)

And in your sub classes, (eg CallerService),

   boolean save(){
     Caller caller = new Caller();
    caller = setCommonProperties(caller);
    caller.setCallerPropertyA(...);
    caller.setCallerPropertyB(...);

    ...

    //save caller
return true or false;
    }