无法获得json：无限递归

Question

在尝试执行GET到发布者存储库时，我正在执行GET和无限循环。

出版商：

@Data
@AllArgsConstructor
@Entity
@Table(name = "publisher")
public class Publisher {

    @Id
    private Long publisherID;

    private String name;
    private String location;

    public Publisher(@JsonProperty("publisherID") Long publisherID,
                     @JsonProperty("name") String name,
                     @JsonProperty("location") String location) {
        this.publisherID = publisherID;
        this.name = name;
        this.location = location;
    }

    @JsonManagedReference(value="Book-Publisher")
    @OneToMany(mappedBy = "publisher", cascade = CascadeType.ALL)
    private Set<Book> books;

    public Publisher() {
    }
}

书：

@Data
@AllArgsConstructor
@Entity
@Table(name = "book")
public class Book {

    @Id

private String name;

@JsonBackReference(value="Book-Publisher")
@ManyToOne
@JoinColumn(name="publisherID")
private Publisher publisher;

private int publicationYear;
private int amount;

@JsonManagedReference(value="BookAuthors-Book")
@OneToMany(mappedBy = "book", cascade = CascadeType.ALL)
private Set<BookAuthors> bookAuthors;

@JsonManagedReference(value="BookGenres-Book")
@OneToMany(mappedBy = "book", cascade = CascadeType.ALL)
private Set<BookGenres> bookGenres;

public Book(@JsonProperty("id") Long id,
            @JsonProperty("name") String name,
            @JsonProperty("publisherID") Long publisherID,
            @JsonProperty("publicationYear") int publicationYear,
            @JsonProperty("amount") int amount) {
    this.id = id;
    this.name = name;
    this.publicationYear = publicationYear;
    this.amount = amount;
    PublisherService publisherService = BeanUntil.getBean(PublisherService.class);
    this.publisher = publisherService.findByID(publisherID).get();

}
@JsonManagedReference(value="RentedBook-Book")
@OneToMany(mappedBy = "book", cascade = CascadeType.ALL)
private Set<RentedBook> rentedBooks;

public Book() {
}

完整代码可在此处获得：

https://github.com/vanyasav/library

Answer 1

当为响应序列化publisher列表时，将调用publisher字段的所有getter方法。因此，publisher关系字段books的getter也被调用来设置值。这是递归发生的，这就是无限递归的原因。

最好不要使用实体作为响应。为publisher创建一个DTO类，然后将publisher实体值映射到DTO中，然后发送响应。

要将一个模型动态映射到另一个模型，可以使用modlemapper