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我刚开始使用EJB。我想用JTA从数据库中接收一些数据。 我的实体：@EJB注入dao
@Entity
@Table(name = "User")
@NamedQuery(name = "User.findByAddressName",
query = "select u from User u where u.userAddress.addressName = :addressName")
public class User implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long userID;
@Column(name = "userFirstName", length = 45)
private String userFirstName;
@Column(name = "userLastName", length = 45)
private String userLastName;
@Column(name = "userBirthDate")
private Date userBirthDate;
@Column(name = "userPhone")
private String userPhone;
@Column(name = "userPassword")
private String userPassword;
@OneToOne(cascade = CascadeType.ALL, mappedBy = "addressUser")
private Email userAddress;
public User() {
}
public User(String userFirstName, String userLastName, Date userBirthDate, String userPhone, String userPassword) {
this.userFirstName = userFirstName;
this.userLastName = userLastName;
this.userBirthDate = userBirthDate;
this.userPhone = userPhone;
this.userPassword = userPassword;
}
}
吾道：
@Stateless
public class UserBean {
@PersistenceContext(unitName = "server")
private EntityManager em;
public User getUserByEmail(String email) {
TypedQuery<User> queryUser = em.createNamedQuery("User.findByAddressName",
User.class);
queryUser.setParameter("addressName", email);
return queryUser.getSingleResult();
}
}
我的服务：
@Stateless
public class LoginService {
@EJB
UserBean userBean;
public boolean loginUser(String userEmail, String userPass) {
User user = userBean.getUserByEmail(userEmail);
if (userPass.equals(user.getUserPassword())) {
return true;
} else return false;
}
}
我尝试收到数据：
boolean b = new LoginService().loginUser("user", "user1");
不过的UserBean的UserBean，通过注入LoginE中的@EJB rvice为null。
有很多关于如何做这些事情的简单例子，我都完全一样，但它仍然抛出NullPointerException，我不知道为什么。