public class AnswerApp {
   public static void main(String[] args) {
        User user = new User(1L, "Answer", "answer_ljm@163.com");
        Card card = new Card(1L, "A0001", "HBCARD", System.currentTimeMillis(), user);
        HbCard hbCard = new HbCard();
        // 注意: 字段名一样， 类型不一样的字段无法复制
        // 将 card 对象的属性值 拷贝到 hbCard 对象(拷贝规则: 字段类型(包装类型和基本类型视为一样)和名称相同)
        org.springframework.beans.BeanUtils.copyProperties(card, hbCard);
      
      // {"cardCode":"A0001","cardName":"HBCARD","id":0,"user":{"email":"answer_ljm@163.com","userId":1,"userName":"Answer"}}
        System.out.println(JSON.toJSONString(hbCard));
    }     
}


@Data
@AllArgsConstructor
class Card {
    private Long id;
    private String cardCode;
    private String cardName;
    private Long createTime;
    private User user;
}


@Data
class HbCard {
    // 基本类型和包装类型可以复制
    private long id;
    private String cardCode;
    private String cardName;
    // 注意 类型不一样
    private String createTime;
    private String updateTime;
    private User user;
}

@Data
@AllArgsConstructor
class User {
    private Long userId;
    private String userName;
    private String email;
}