1.添加@TableField注解

    /**
     * 创建时间
     */
    @TableField(fill = FieldFill.INSERT) // 插入时生效
    private LocalDateTime createTime;

    /**
     * 修改时间
     */
    @TableField(fill = FieldFill.INSERT_UPDATE) // 插入和更新时生效
    private LocalDateTime updateTime;

2.添加TimeMetaObjectHandler配置

@Component
public class TimeMetaObjectHandler implements MetaObjectHandler {

    /**
     * 新增时的操作
     * @param metaObject 元对象
     */
    @Override
    public void insertFill(MetaObject metaObject) {
        if (ObjectUtil.isEmpty(metaObject) || !(metaObject.getOriginalObject() instanceof BaseEntity)) {
            return;
        }
        BaseEntity baseEntity = (BaseEntity) metaObject.getOriginalObject();
        LocalDateTime createTime = ObjectUtil.isNotNull(baseEntity.getCreateTime())
                ? baseEntity.getCreateTime() : LocalDateTime.now().withNano(0);
        LocalDateTime updateTime = ObjectUtil.isNotNull(baseEntity.getUpdateTime())
                ? baseEntity.getUpdateTime() : LocalDateTime.now().withNano(0);
        baseEntity.setCreateTime(createTime);
        baseEntity.setUpdateTime(updateTime);
    }

    /**
     * 修改时的操作
     * @param metaObject 元对象
     */
    @Override
    public void updateFill(MetaObject metaObject) {
        if (ObjectUtil.isEmpty(metaObject) || !(metaObject.getOriginalObject() instanceof BaseEntity)) {
            return;
        }
        BaseEntity baseEntity = (BaseEntity) metaObject.getOriginalObject();
        LocalDateTime updateTime = LocalDateTime.now().withNano(0);
        baseEntity.setUpdateTime(updateTime);
    }
}

3.测试

达到预期要求。