Lombok.hashCode issue with "java.lang.StackOverflowError: null"

Question

我有两个表具有如下一对一关系：

@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Book {
  @Id
  @GeneratedValue(strategy = GenerationType.TABLE)
  private int id;

  private String name;

  @OneToOne(cascade = CascadeType.ALL)
  @JoinColumn(name = "book_dtail_id")
  private BookDetail bookDetail;
}

@Entity
@Table(name = "book_detail")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class BookDetail {
  @Id
  @GeneratedValue(strategy = GenerationType.TABLE)
  private Integer id;

  @Column(name = "number_of_pages")
  private Integer numberOfPages;

  @OneToOne(mappedBy = "bookDetail")
  private Book book;
}

我使用表格输入数据如下

@Data
@NoArgsConstructor
@AllArgsConstructor
public class BookForm {
  Book book;
  BookDetail bookDetail;
}

控制器看起来像这样：

String handleNewBook(Model model){
  Book book = new Book();
  BookDetail bookDetail = new BookDetail();
  BookForm bookForm = new BookForm(book, bookDetail);

  model.addAttribute("bookForm", bookForm);
  return "index";
}

String handleSaveBookCreate(BookForm bookForm, Model model){
    bookForm.getBook().setBookDetail(bookForm.getBookDetail());
    bookForm.getBookDetail().setBook(bookForm.getBook());
    bookService.save(bookForm.getBook()));
    return "index";
}

最后是我的表格如下：

<form role="form" action="#" th:object="${bookForm}" th:action="@{/book}" method="POST">
    <input type="text" th:field="*{book.name}"/>
    <input type="text" th:filed="*{bookDetail} == null ? '' : *{bookDetail.numberOfPages}"  placeholder="Enter Book Page Numbers"/>
    <button type="submit">Submit</button>
</form>

一切似乎都没有问题，但是当我执行"bookService.save(bookForm.getBook()));"时，出现如下错误

java.lang.WhosebugError: null, 
at com.zangland.study.jpa.entity.BookDetail.hashCode(BookDetail.java:17) ~[classes/:na]
at com.zangland.study.jpa.entity.Book.hashCode(Book.java:16) ~[classes/:na]
at com.zangland.study.jpa.entity.BookDetail.hashCode(BookDetail.java:17) ~[classes/:na]
at com.zangland.study.jpa.entity.Book.hashCode(Book.java:16) ~[classes/:na]

和上面一样重复大约 100 行....这是否意味着我不能使用 Lombok.hashCode？

保存的书：“32768”，'Spring JPA'，“32768” 保存的 BookDetail：“32768”、“1157”

Answer 1

您在 book 和 bookdetails 之间存在循环依赖。您可能需要从 BookDetail 中排除 book 或从 Book 中排除 bookDetail。

您可以添加 @EqualsAndHashCode(exclude="book")。有关详细信息，请参阅 EqualsAndHashCode documentation.

Answer 2

lambok 导致循环依赖

原因：toString() 方法

解决方法：将您的其中一个模型替换为

@Getter
@Setter
public class BookDetail

而不是

@Data
public class BookDetail

Lombok.hashCode issue with "java.lang.StackOverflowError: null"

Lombok.hashCode issue with "java.lang.StackOverflowError: null"

hashcode

lombok