java - Single DAO & generic CRUD methods (JPA/Hibernate + Spring) -

following previous question, dao , service layers (jpa/hibernate + spring), decided use single dao data layer (at least @ beginning) in application using jpa/hibernate, spring , wicket. use of generic crud methods proposed, i'm not sure how implement using jpa. please give me example or share link regarding this?

here example interface:

public interface genericdao<t, pk extends serializable> {     t create(t t);     t read(pk id);     t update(t t);     void delete(t t); } 

and implementation:

public class genericdaojpaimpl<t, pk extends serializable>      implements genericdao<t, pk> {      protected class<t> entityclass;      @persistencecontext     protected entitymanager entitymanager;      public genericdaojpaimpl() {         parameterizedtype genericsuperclass = (parameterizedtype) getclass()              .getgenericsuperclass();         this.entityclass = (class<t>) genericsuperclass              .getactualtypearguments()[0];     }      @override     public t create(t t) {         this.entitymanager.persist(t);         return t;     }      @override     public t read(pk id) {         return this.entitymanager.find(entityclass, id);     }      @override     public t update(t t) {         return this.entitymanager.merge(t);     }      @override     public void delete(t t) {         t = this.entitymanager.merge(t);         this.entitymanager.remove(t);     } }