Question

我有两个表有一对一的关系，如下所示：

@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;
}

我使用表单输入数据如下

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

控制器如下所示：

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>

一切似乎没有问题，但是当我＆＃34; bookService.save（bookForm.getBook（）））;＆＃34;执行，我得到如下错误

java.lang.StackOverflowError: 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]

重复上述大约100行......这是否意味着我不能使用Lombok.hashCode？

已保存的图书：＆＃39; 32768＆＃39;，＆＃39;春天JPA＆＃39; 32768＆＃39; 保存的书籍详细信息：＆＃39; 32768＆＃39;，＆＃39; 1157＆＃39;

Answer 1

书与书籍之间存在循环依赖关系。您可能需要从book排除BookDetail或从bookDetail排除Book。

Answer 2

lambok导致循环依赖

原因：toString（）方法

解决方案：替换您的模型之一

@Getter
@Setter
public class BookDetail

代替

@Data
public class BookDetail

Lombok.hashCode问题＆＃34; java.lang.StackOverflowError：null＆＃34;

2 个答案: