如何在JSP

Question

我有两个具有OneToMany关系的对象，外键是userName。当我检查数据库时，我可以在那里看到外键。但我不知道为什么我什么也得不到。

JSP

//ERROR HERE, I CAN'T GET DATA OF THE FOREIGN KEY 'USERNAME'
<div class="row">
    <label class="col-sm-2">Owner</label>
    <div class="col-sm-10">${book.myUserAccount.userName}</div>
</div>

<div class="row">
    <label class="col-sm-2">Book's Name</label>
    <div class="col-sm-10">${book.tensach}</div>
</div>

<div class="row">
    <label class="col-sm-2">Author</label>
    <div class="col-sm-10">${book.tacgia}</div>
</div>

<div class="row">
    <label class="col-sm-2">Review</label>
    <div class="col-sm-10">${book.nhanxet}</div>
</div>

模型MyUserAccount

public class MyUserAccount implements Serializable {

private static final long serialVersionUID = 1L;
public static final String ROLE_USER = "ROLE_USER";
private String id;
private String email;
private String userName;
private String firstName;
private String lastName;
private String password;
private String role;
private String enabled;
private List<Book> book = new ArrayList<Book>(0);
private List<BookTrade> bookTrade = new ArrayList<BookTrade>(0);

public MyUserAccount() {

}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "myUserAccount")
public List<Book> getBook() {
    return book;
}

public void setBook(List<Book> book) {
    this.book = book;
}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "myUserAccount")
public List<BookTrade> getBookTrade() {
    return bookTrade;
}

public void setBookTrade(List<BookTrade> bookTrade) {
    this.bookTrade = bookTrade;
}

public MyUserAccount(String id, String email, String userName, String firstName, //
        String lastName, String password, String role, String enabled) {
    this.id = id;
    this.email = email;
    this.userName = userName;
    this.firstName = firstName;
    this.lastName = lastName;
    this.password = password;
    this.role = role;
    this.enabled = enabled;
}

@Column(name = "ID", unique = true, nullable = false)
public String getId() {
    return id;
}

模特书

public class Book implements Serializable {

private static final long serialVersionUID = 1L;
private Integer book_ID;
private String tensach;
private String tacgia;
private String nhanxet;
private String tinhtrang;
private String theloai;
private byte[] image;
private String image_name;
private String data;
private MyUserAccount myUserAccount;

public Book() {

}

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "USER_NAME", nullable = false)
public MyUserAccount getMyUserAccount() {
    return this.myUserAccount;
}

public void setMyUserAccount(MyUserAccount myUserAccount) {
    this.myUserAccount = myUserAccount;
}

@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "book_id", unique = true, nullable = false)
public Integer getBook_ID() {
    return book_ID;
}

我如何映射两个对象：

控制器

public String saveBook(@ModelAttribute("bookForm") @Validated Book book, BindingResult result, Model model,
        @RequestParam CommonsMultipartFile[] image, @RequestParam String userName, final RedirectAttributes redirectAttributes)
        throws IOException, UnsupportedEncodingException {

    MyUserAccount myUserAccount = myUserAccountDAO.findByUserName(userName);
    book.setMyUserAccount(myUserAccount);

    redirectAttributes.addFlashAttribute("css", "success");
    if (book.getBook_ID() == null) {
        System.out.println(book.getBook_ID());
        redirectAttributes.addFlashAttribute("msg", "book added successfully!");
    } else {
        redirectAttributes.addFlashAttribute("msg", "book updated successfully!");
    }

    for (CommonsMultipartFile aFile : image) {
        System.out.println("Saving file: " + aFile.getOriginalFilename());
        book.setImage_name(aFile.getOriginalFilename());
        book.setImage(aFile.getBytes());
        System.out.println("Damn that Shit!");
    }
    bookService.saveOrUpdate(book);
    // POST/REDIRECT/GET
    return "redirect:/motsach/" + book.getBook_ID();
}

DAO

public void save(Book book) {
    // TODO Auto-generated method stub
    KeyHolder keyHolder = new GeneratedKeyHolder();
    String sql = "INSERT INTO Books(TENSACH, TACGIA, NHANXET, TINHTRANG, THELOAI, IMAGE, IMAGE_NAME, USER_NAME) "
            + "VALUES ( :tensach, :tacgia, :nhanxet, :tinhtrang, :theloai, :image, :image_name, :user_name)";

    namedParameterJdbcTemplate.update(sql, getSqlParameterByModel(book), keyHolder);
    book.setBook_ID(keyHolder.getKey().intValue());
}

private SqlParameterSource getSqlParameterByModel(Book book) {
    MapSqlParameterSource paramSource = new MapSqlParameterSource();
    paramSource.addValue("book_id", book.getBook_ID());
    paramSource.addValue("tensach", book.getTensach());
    paramSource.addValue("tacgia", book.getTacgia());
    paramSource.addValue("nhanxet", book.getNhanxet());
    paramSource.addValue("tinhtrang", book.getTinhtrang());
    paramSource.addValue("image", book.getImage());
    paramSource.addValue("image_name", book.getImage_name());
    paramSource.addValue("theloai", book.getTheloai());
    paramSource.addValue("user_name", book.getMyUserAccount().getUserName());
    return paramSource;
}