Question

有关数据库的详细信息： folder_Meta_Data有字段ID，parentFolderId，其中id只有folderid就像主键一样，parentFolderId表示id。

@Entity
@Table(name = "folder_Meta_Data")
@Data
@JsonInclude(JsonInclude.Include.ALWAYS)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id",scope=FolderMetaData.class)
public class FolderMetaData implements Serializable {

    @Id
    @SequenceGenerator(name = "seq-gen", initialValue = 1)
    @GeneratedValue(strategy = GenerationType.IDENTITY, generator = "seq-gen")
    @Column(name = "id", nullable = false)
    private Long id;

    @Column(name = "projectId", nullable = false)
    private Long projectId;
    @Column(name = "mgId", nullable = false)
    private Long mgId;
    @Column(name = "folderRoot", length = 50)
    private String folderRoot;
    @Column(name = "folderExtention", length = 50)
    private String folderExtention;
    @Column(name = "folderName", nullable = false, length = 255)
    private String folderName;
    @Column(name = "createdBy", nullable = false)
    private Long createdBy;
    @Column(name = "createdTime", nullable = false)
    private Date createdTime;
    @Column(name = "versionOCC")
    private Long versionOCC;
    @Column(name = "subProjId", nullable = false)
    private Long subProjId;
    @Column(name = "modifiedBy")
    private Long modifiedBy;
    @Column(name = "modifiedTime", length = 50)
    private Date modifiedTime;
    @Column(name = "parentFolderId")
    private Long parentFolderId;

    @ManyToOne(cascade = { CascadeType.ALL })
    @JoinColumn(name = "parentFolderId", insertable = false, updatable = false)
    @JsonBackReference
    // @JsonIgnore
    // child role
    private FolderMetaData folder;

    @OneToMany(mappedBy = "folder")
    // parent role
    @JsonManagedReference
    private Set<FolderMetaData> folderList;

    // Getter and Setter methods
}

JSON树响应：

The response i am getting is  as below
[
    {
        "id": 1,
        "projectId": 125,
        "mgId": 34512,
        "folderRoot": null,
        "folderExtention": null,
        "folderName": "XY1",
        "createdBy": 12,
        "createdTime": "2018-03-16",
        "versionOCC": null,
        "subProjId": 561565,
        "modifiedBy": null,
        "modifiedTime": null,
        "parentFolderId": null,
        "folderList": []
    },
    {
        "id": 2,
        "projectId": 125,
        "mgId": 34512,
        "folderRoot": null,
        "folderExtention": null,
        "folderName": "XY2",
        "createdBy": 12,
        "createdTime": "2018-03-16",
        "versionOCC": null,
        "subProjId": 561565,
        "modifiedBy": null,
        "modifiedTime": null,
        "parentFolderId": null,
        "folderList": [
            {
                "id": 3,
                "projectId": 125,
                "mgId": 34512,
                "folderRoot": null,
                "folderExtention": null,
                "folderName": "XY2",
                "createdBy": 12,
                "createdTime": "2018-03-16",
                "versionOCC": null,
                "subProjId": 561565,
                "modifiedBy": null,
                "modifiedTime": null,
                "parentFolderId": 2,
                "folderList": [
                    {
                        "id": 4,
                        "projectId": 125,
                        "mgId": 34512,
                        "folderRoot": null,
                        "folderExtention": null,
                        "folderName": "XY2",
                        "createdBy": 12,
                        "createdTime": "2018-03-16",
                        "versionOCC": null,
                        "subProjId": 561565,
                        "modifiedBy": null,
                        "modifiedTime": null,
                        "parentFolderId": 3,
                        "folderList": [
                            {
                                "id": 5,
                                "projectId": 125,
                                "mgId": 34512,
                                "folderRoot": null,
                                "folderExtention": null,
                                "folderName": "XY2",
                                "createdBy": 12,
                                "createdTime": "2018-03-16",
                                "versionOCC": null,
                                "subProjId": 561565,
                                "modifiedBy": null,
                                "modifiedTime": null,
                                "parentFolderId": 4,
                                "folderList": []
                            }
                        ]
                    }
                ]
            }
        ]
    },
    3,
    4,
    5
]

在服务类方法中，我在下面调用方法来检索所有记录。由于它是Jackson api，所有获取的记录都作为父母和孩子的关系填充到列表中。记录得到json树。

    List<FolderMetaData> list=folderRepository.findAll();

问题是： 在FolderMetaData pojo中使用@JsonBackReference和@JsonManagedReference之后。

The tree is coming correctly. but in the bottom of this json array response, I am getting dirty data which are ids of subtrees. if anyone help me to fix this issue, that would be great.

如下所示

Answer 1

我认为您的问题是lombok @Data，它会生成引用您自引用属性的toString，equals和hascode方法。这会产生stackoverflow错误，这与序列化无关，但根本原因是相同的（自引用）。请按照文档中的说明使用lombok Exclude或使用@Getter @Setter并自行实施此方法。

Answer 2

问题是你从数据库中获取所有数据，你可以在这里查看Spring boot + (JPA) - Category hierarchy - recursively traverse，他有同样的问题

Java Hibernate json无限递归，自引用类2

2 个答案: