春季休眠一对多不显示

Question

我正在尝试构建一个具有两种对象的网络应用程序：书籍和评论（一本书可以有多个评论）。

我可以看到书籍列表，但是当我进入书籍页面时，我可以看到书籍的标题和其他属性，但评论的属性不会显示，我不知道为什么。我只能看到一个带有空值的单行的空表。

我认为它无法识别该对象，因为审查表中有三个条目，所以如果它能够识别该表，那么该表就有三行。

Book.java

@Entity
@Table(name = "BOOK")
public class Book {

    private int bookId;
    private int bookRating;
    private String bookCategory;
    private String bookAuthor;
    private String bookTitle;

    @Transient
    private Set<Review> review;

    @Transient  
    private List<String> reviews;

    public Book() {}

    public Book(String title) {
        this.bookTitle = title;
    }

    @Id
    @GeneratedValue
    @Column(name = "BOOKID")
    public int getBookid() {
        return bookId;
    }

    ...

    @OneToMany
    @JoinColumn(name="r_bookid")
    public Set<Review> getReviews() {
        return review;
    }

    public void setReviews(Set<Review> reviews) {
        this.review = review;
    }
}

Review.java

@Entity
@Table(name = "REVIEW")
public class Review {

private int id;
private Date r_date;
private String r_author;
private String r_text;
private int r_rating;
@Transient
private Set<Review> review;
private Book book;
private int r_bookid;

public Review(String author, String text, Date date, int rating, int bookid, Book book) {   
    super();
    this.r_author = author;
    this.r_text = text;
    this.r_date = date;
    this.r_rating = rating;
    this.r_bookid = bookid;
    this.book= book;
}

@Id
@GeneratedValue
@Column(name = "ID")
public int getId() {
    return id;
}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "book", cascade = CascadeType.ALL)
public Set<Review> getReviews() {
    return review;
}

BookDAOImpl.java

@Override
@Transactional
public Set<Review> getReviews() {
  Set<Review> listReview = (Set<Review>) sessionFactory.getCurrentSession()
    .createCriteria(Review.class)
    .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();
  return listReview;
}

Controller.java

@RequestMapping(value = "/book", method = RequestMethod.GET)
public ModelAndView viewBook(HttpServletRequest request) {
  int bookId = Integer.parseInt(request.getParameter("id"));
  Book book = bookDao.get(bookId);
  Set<Review> review = book.getReviews();
  ModelAndView model = new ModelAndView("viewBook");
  model.addObject("book", book);
  model.addObject("review", review);      
  return model;  
 }

viewBook.jsp

<h1>Carte: ${book.bookTitle}</h1>
<h2>Autor: ${book.bookAuthor}</h2>

<c:forEach var="rev" items="${review}" varStatus="status">
<tr>
  <td>${status.index + 1}</td>
  <td>${rev.r_author}</td>
  <td>${rev.r_text}</td>
  <td>${rev.r_date}</td>
  <td>${rev.r_rating}</td> 
</tr>
</c:forEach>             

数据库表

CREATE DATABASE test;

CREATE TABLE `book` (
  `bookId` int(11) NOT NULL AUTO_INCREMENT,
  `bookTitle` varchar(45) NOT NULL,
  `bookAuthor` varchar(45) NOT NULL,
  `bookCategory` varchar(45) NOT NULL,
  `bookRating` int(11) NOT NULL,
  PRIMARY KEY (`bookId`)
);

CREATE TABLE `review` (
  `id` int(11) NOT NULL,
  `r_author` varchar(45) NOT NULL,
  `r_text` varchar(205) NOT NULL,
  `r_rating` int(11) NOT NULL,
  `r_date` date NOT NULL,
  `r_bookid` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `r_bookid_idx` (`r_bookid`),
  CONSTRAINT `r_bookid` FOREIGN KEY (`r_bookid`) REFERENCES `book` (`bookId`) ON DELETE CASCADE
);

Answer 1

移除@Transient 注解。此注解指定不保留带注解的字段。

Answer 2

您的映射本身似乎有问题。

请看一下这个blog post。我想它可能会对你有所帮助。