如何通过Jackson将嵌套JSON字段映射到Hibernate实体直接属性

从REST API获取到指定JSON数据，当前通过中间类AnnouncementExternalIds实现Jackson JSON映射，但希望将announcementCustomerIDs、announcementOfficeIDs、announcementPositionIDs直接映射到Announcement实体的属性上，以便更便捷地使用Hibernate将对象保存到数据库。

返回的JSON结构 #

{
    "announcementData": [
        {
            "departmentId": 1,
            "announcementId": 12345,
            "announcementNumber": "Test Ann",
            "announcementExternalIDs": {
                "announcementCustomerIDs": [
                    {
                        "departmentId": 1,
                        "announcementId": 12345,
                        "customerId": 111
                    }
                ],
                "announcementOfficeIDs": [
                    {
                        "departmentId": 1,
                        "announcementId": 12345,
                        "officeId": 1
                    }
                ],
                "announcementPositionIDs": [
                    {
                        "departmentId": 1,
                        "announcementId": 12345,
                        "positionId": 98765
                    }
                ]
            }
        }
    ]
}

当前映射实现 #

当前通过中间类承接嵌套的ID列表：

Announcement实体（当前） #

@Entity
@Table(name = "ANNOUNCEMENT")
public class Announcement {
  @Id
  @JsonProperty("announcementId")
  private long announcementId;

  @JsonProperty("departmentId")
  private int departmentId;

  @JsonProperty("announcementNumber")
  private String announcementNumber;

  @JsonProperty("announcementExternalIDs")
  private AnnouncementExternalIds announcementExternalIDs;
}

AnnouncementExternalIds中间类 #

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"announcementCustomerIDs", "announcementOfficeIDs", "announcementVacancyIDs"})
public class AnnouncementExternalIds {
  @JsonProperty("announcementCustomerIDs")
  private List<AnnouncementCustomerId> announcementCustomerIds = new ArrayList<>();

  @JsonProperty("announcementOfficeIDs")
  private List<AnnouncementOfficeId> announcementOfficeIds = new ArrayList<>();

  @JsonProperty("announcementPositionIDs")
  private List<AnnouncementPositionID> announcementPositionIDs= new ArrayList<>();
}

AnnouncementCustomerId实体 #

@Entity
@Table(name = "ANNOUNCEMENT_CUSTOMER_ID")
public class AnnouncementCustomerId {
  @JsonProperty("departmentId")
  private String departmentId;

  @JsonProperty("announcementId")
  private String announcementId;

  @Id
  @JsonProperty("customerId")
  private String customerId;
}

期望的实体结构 #

希望直接将嵌套的ID列表映射到Announcement实体属性，无需中间类：

@Entity
@Table(name = "ANNOUNCEMENT")
public class Announcement {
  @Id
  @JsonProperty("announcementId")
  private long announcementId;

  @JsonProperty("departmentId")
  private int departmentId;

  @JsonProperty("announcementNumber")
  private String announcementNumber;

  @JsonProperty("announcementCustomerIDs")
  private List<AnnouncementCustomerId> announcementCustomerIds = new ArrayList<>();

  @JsonProperty("announcementOfficeIDs")
  private List<AnnouncementOfficeId> announcementOfficeIds = new ArrayList<>();

  @JsonProperty("announcementPositionIDs")
  private List<AnnouncementPositionID> announcementPositionIDs= new ArrayList<>();
}

利用Jackson的属性路径映射功能，通过@JsonProperty指定嵌套属性的完整路径，即可跳过中间类直接完成映射。

修改后的Announcement实体类 #

@Entity
@Table(name = "ANNOUNCEMENT")
public class Announcement {
  @Id
  @JsonProperty("announcementId")
  private long announcementId;

  @JsonProperty("departmentId")
  private int departmentId;

  @JsonProperty("announcementNumber")
  private String announcementNumber;

  // 直接映射嵌套在announcementExternalIDs下的announcementCustomerIDs
  @JsonProperty("announcementExternalIDs.announcementCustomerIDs")
  private List<AnnouncementCustomerId> announcementCustomerIds = new ArrayList<>();

  // 直接映射嵌套在announcementExternalIDs下的announcementOfficeIDs
  @JsonProperty("announcementExternalIDs.announcementOfficeIDs")
  private List<AnnouncementOfficeId> announcementOfficeIds = new ArrayList<>();

  // 直接映射嵌套在announcementExternalIDs下的announcementPositionIDs
  @JsonProperty("announcementExternalIDs.announcementPositionIDs")
  private List<AnnouncementPositionID> announcementPositionIDs = new ArrayList<>();

  // 需添加getter、setter方法，满足Hibernate属性访问要求
}

额外配置说明 #

1. Hibernate关联配置：为了顺利保存到数据库，需要为Announcement与关联实体配置正确的关联注解，示例如下：

   @OneToMany(mappedBy = "announcement", cascade = CascadeType.ALL, orphanRemoval = true)
   @JsonProperty("announcementExternalIDs.announcementCustomerIDs")
   private List<AnnouncementCustomerId> announcementCustomerIds = new ArrayList<>();
   

   同时在关联实体（如AnnouncementCustomerId）中添加Announcement引用：

   @ManyToOne
   @JoinColumn(name = "announcement_id")
   private Announcement announcement;
   

2. 版本兼容性：确保使用Jackson 2.x及以上版本，该版本支持属性路径映射功能。
3. 属性名匹配：注解中指定的路径需与JSON中的属性名完全一致，包括大小写。

内容的提问来源于stack exchange，提问作者Tony