java - spring mvc Controller 中的无限json序列化

Question

我有以下映射:

1

public class Content {

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "content_id", unique = true, nullable = false)
    private Long contentId;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "content", cascade = CascadeType.ALL)
    UserContent userContent;
     ....
}

<小时/>

@Entity
@Table(name="user_content")
public class UserContent {
    @GenericGenerator(name = "generator", strategy = "foreign", parameters = @Parameter(name = "property", value = "content"))
    @Id
    @GeneratedValue(generator = "generator")
    @Column(name = "content_id", unique = true, nullable = false)
    private Long contentId;

    @OneToOne(fetch = FetchType.EAGER)
    @PrimaryKeyJoinColumn
    Content content;
}

以及以下 dao:

 public Set<UserContent> getAllContent() {
        Session session = sessionFactory.getCurrentSession();
        return new HashSet<UserContent>(session.createCriteria(UserContent.class).list());
    }

当在 Controller 方法中返回此 dao 的结果时，我看到无限递归 json:

[{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":{"contentId":1,"name":"DSC_0029.JPG","moderationStatus":"IN_PROGRESS","moderateComment":"","content":{"userContent":....

2

我尝试像这样更改映射:

import com.fasterxml.jackson.annotation.JsonIgnore;

public class Content {
    ...
    @OneToOne(fetch = FetchType.LAZY, mappedBy = "content", cascade = CascadeType.ALL)
    @JsonIgnore        //added this annotation
    UserContent userContent;
    ....

结果:

HTTP Status 500 - Could not write JSON: failed to lazily initialize a collection of role: com.terminal.domain.TerminalUser.companys, no session or session was closed (through reference chain: java.util.HashSet[0]->com.terminal.domain.UserContent["user"]->com.terminal.domain.TerminalUser["companys"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.terminal.domain.TerminalUser.companys, no session or session was closed (through reference chain: java.util.HashSet[0]->com.terminal.domain.UserContent["user"]->com.terminal.domain.TerminalUser["companys"])

附注

我已阅读以下热门答案，但我无法解决我的问题 - 请帮助。

Infinite Recursion with Jackson JSON and Hibernate JPA issue

Answer 1

自 Jackson 2.0 起，您可以使用 @JsonIdentityInfo。 检查documentation

已更新

...
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id")
public class Content {
    ...
}

...
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id")
public class UserContent {
    ...
}