JPARepository.java 文件源码

@Override
public Optional<MODEL> update(MODEL model) throws RuntimeException {
    checkModelNullity(model);

    Optional<MODEL> possibleModel = findById(model.getId());
    possibleModel.ifPresent(found -> {
        try {
            checkIfCollides(model);

            EntityTransaction tr = em.getTransaction();
            tr.begin();
            found.updateWith(model);
            tr.commit();
        } finally {
            em.detach(found);
        }
    });

    return possibleModel;
}