为什么 JPA 2.2 将 java.util.Date 存储为 null

Question

我有一个 Java EE 实体 class 包含一个 java.util.Date 字段。由于某种原因未存储此字段的值。

@Entity
@Table(name = "PERSISTENCE_USER")
@NamedQueries({
@NamedQuery(name = "findAllusers",
        query = "SELECT U FROM User u "
        + "ORDER BY u.userId"
),
@NamedQuery(name = "getAUser",
        query = "SELECT U FROM User u "
        + "WHERE u.userId =?1 AND u.password=?2 "
        + "ORDER BY u.userId"
)
})
public class User implements Serializable {

    private static final long serialVersionUID = 10044331905L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @NotNull
    private String firstName;
    @NotNull
    private String lastName;
    @Temporal(TemporalType.TIMESTAMP)
    private Date dateOfBirth;
............
}

这是一个单例，它填充 table 中的一行：

@Singleton
@Startup
@ConcurrencyManagement(ConcurrencyManagementType.CONTAINER)
public class DataLoaderSessionBean {
    @EJB
    private LoginRequestSessionBean requestLogin;
    @PostConstruct
    public void createData() {
        try {
            List<User> users = new ArrayList();
            Date date = new Date(System.currentTimeMillis());
            users.add(new User("Joe","Ottaviano",date));
            users.add(new User("Partrick","Tucker",date));
            requestLogin.addUsers(users);
        } catch (Exception e) {
    }
}

稍后当我检索并检查数据时，日期字段为空：

@Stateful
public class LoginRequestSessionBean {
     @PersistenceContext
    EntityManager em;

    public void addUsers(List<User> users) throws EJBException {
            users
                .stream()
                .forEach(this::addUser);
    }
    public void addUser(User u) throws EJBException {
        try {
            if (em != null) {
                if (em.isOpen()) {
                    if (u != null) {
                        em.persist(u);
                    } else {
                        throw (new EJBException("NULL user can not be added"));
                    }
                } else {
                    throw (new EJBException("EntityManager is closed"));
                }
            } else {
                throw (new EJBException("EntityManager is NULL"));
            }
        } catch (EntityManagerSetupException e) {
            System.out.println("Caught an Exception: "+ e.getMessag();
            throw e;
        }
    }
public List<User> getUsers() throws EJBException{
        logger.entering(className, "getUsers()");
        List<User> users = null;
        try {
            if (em != null) {
                if (em.isOpen()) {
                    Query q = em.createNamedQuery("findAllusers");
                    users = (List<User>) q.getResultList();
                    for (User user : users){
                        Date d = user.getDateOfBirth();
                        if(d == null){
                            System.out.println("The dob for user "+user.getLasName()+" null);
                        }
                    }
                } else {
                    throw (new EJBException("EntityManager is closed"));
                }
            } else {
                throw (new EJBException("EntityManager is NULL"));
            }
        } catch (EntityManagerSetupException e) {
            System.out.println(e.getMessage());
            throw new EJBException(e.getMessage());
        }
        return users;
    }
}

知道如何存储 java.util.Date 的值吗？

Answer 1

您发布的代码似乎是正确的。您应该检查 User class 中的构造函数是否设置了 dateOfBirth 字段。

为什么 JPA 2.2 将 java.util.Date 存储为 null

Why JPA 2.2 stores java.util.Date as null

java

ejb

jpa-2.2