從jpa捕獲ConstraintViolationException給出約束名稱為空值

Question

我使用jpa和hibernate來保存數據。我的模型是

@Entity
@Table(name = "user", uniqueConstraints=@UniqueConstraint(columnNames={"username"}, name="username"))
public class User implements Serializable {
    @Transient
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    @Column(name = "username", nullable = false)
    private String username;

    @Column(name = "password", nullable = false)
    private String password;

    @Column(name = "user_role", nullable = false)
    private UserRole userRole;
}   

如果用戶違反了唯一值，我將捕獲ConstraintViolationException以進行捕獲。 但是當我嘗試使用ConstraintViolationException.getConstraintName（）訪問constraintName時，會給我空值。 我怎么知道哪一列違反了約束以警告用戶？

Answer 1

嘗試： cve.getCause().getMessage()