JPA中@CreatedDate和@LastModifiedDate的使用方式

//@Data lombok注解，替我们生成getter和setter。
@Data
@Entity
@Table(name = "task")
@EntityListeners(AuditingEntityListener.class)
public class Task {
    /**
     * 自增主键
     */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    /**
     * 创建时间
     */
    @CreatedDate
    @Column(name = "createTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date createTime;

    /**
     * 更新时间
     */
    @LastModifiedDate
    @Column(name = "updateTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date updateTime;
}

@EnableJpaAuditing
@SpringBootApplication
public class TestApplication {
    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    } 
}

@Data
@Entity
@EntityListeners(AuditingEntityListener.class)
public class Task {

  	/**
     * 自增主键
     */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    /**
     * 创建时间
     */
    @CreatedDate
    @Column(name = "createTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date createTime;

    /**
     * 更新时间
     */
    @LastModifiedDate
    @Column(name = "updateTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date updateTime;
    
     /**
     * 创建人
     */
    @CreatedBy
    @Column(name = "createBy", columnDefinition = "varchar(255) not null")
    private String createBy;

    /**
     * 最后修改人
     */
    @LastModifiedBy
    @Column(name = "lastModifiedBy", columnDefinition = "varchar(255) not null")
    private String lastModifiedBy;
}

/**
 * Spring Data JPA通过AuditorAware<T>接口获取用户信息,
 * 其中泛型T可以为String保存用户名，也可以为Long/Integer保存用户ID。
 * @author EvanWang
 *
 */
@Component
public class AuditorConfig implements AuditorAware<String> {

    /**
     * 返回操作员标志信息
     *
     * @return
     */
    @Override
    public Optional<String> getCurrentAuditor() {
        // 这里应根据实际业务情况获取具体信息
        return Optional.of(userName);
    }
}

@Data
@MappedSuperclass
@NoArgsConstructor
@AllArgsConstructor
public class Task {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @UpdateTimestamp
    @Column(name = "updateTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date updateTime;

    @CreationTimestamp
    @Column(name = "updateTime", columnDefinition = "timestamp not null default current_timestamp")
    private Date createTime;
}