spring - Generic DAO - "Never go full generic!" -

ive seen allot of usages of generic dao on internet. gotta love it:

public interface genericdao <t, pk extends serializable> {}  public class genericdaohibernateimpl <t, pk extends serializable> implements genericdao<t, pk> 

a new class appeared? no problem:

public interface newclassdao extends genericdao<newclass, long>  

and we're set.

now, how bad if go "full-generic" , like:

public interface fullgenericdao   public class fullgenericdaohibernateimpl 

now can use 1 dao (of object casting!)

a new class appeared again? no problem:

newclassapperedagain newclassappeared = (newclassapperedagain) fullgenericdao.getitembyid(20, newclassapperedagain.class); 

two questions comes mind:

1) possible go "full-generic" , create such dao? mean dont see why not passing every method of dao classname , casting neccessary? save(object,classname); delete(object,classname); etc..

2) cons (i'm sure there are) of such practice?

thanks!

dao objects there contain domain model specific logic connected persistence layer.

you can go full generic, have face questions like:

• where should put logic connected searching (e.g. constructing clause)?
  • user finduserbyorganizationid(serializable organizationid)
• where put specific mapping functions (e.g. aggregate queries)?
  • map<organization, integer> findusercountperorganization()

i pretty sure there other architectural / logical issues. generics erased during runtime have introduced necessity include domain object class<?> in every method signature.

tl;dr possible "go full generic", need move non-shared persistence logic higher levels. better shared generic logic in abstractdaoimpl , subclass that. might end empty implementations (the generic superclass might have need), have place future domain model specific methods.