5.4. EntityManager

 
@Repository
@Transactional(readOnly = true) 
class AccountServiceImpl implements AccountService { 

  @PersistenceContext
  private EntityManager em; 

  @Override
  @Transactional
  public Account save(Account account) { 

    if (account.getId() == null) { 
      em.persist(account); 
      return account; 
    } else { 
      return em.merge(account); 
    } 
  } 

  @Override
  public List<Account> findByCustomer(Customer customer) { 

    TypedQuery query = em.createQuery("select a from Account a where a.customer = ?1", Account.class); 
    query.setParameter(1, customer); 

    return query.getResultList(); 
  } 
 
  @Override
  public List<Customer> findAll(int page, int pageSize) { 

    TypedQuery query = em.createQuery("select c from Customer c", Customer.class); 

    query.setFirstResult(page * pageSize); 
    query.setMaxResults(pageSize); 

    return query.getResultList(); 
  } 
  
} 
  

原文出处：Netkiller 系列 手札
本文作者：陈景峯
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