问EJB JPA体系结构

EN

public abstract class GenericServiceImpl<T, PK> implements GenericService<T, PK> {

    @PersistenceContext
    protected EntityManager em;

    private Class<T> type;

    public GenericServiceImpl(Class<T> t) {
        this.type = t;
    }

    @Override
    public T create(final T t) {
        this.em.persist(t);
        return t;
    }

    @Override
    public void delete(final PK id) {
        this.em.remove(this.em.getReference(type, id));
    }

    @Override
    public T find(final PK id) {
        return (T) this.em.find(type, id);
    }

    @Override
    public T update(final T t) {
        return this.em.merge(t);    
    }
}