使用注释验证值对象

Question

我决定使用实体中的值对象而不是字符串字段，我不知道使用@Size，例如@Size，@pattern等。这是我的书实体：

   @Entity
@Access(AccessType.FIELD) // so I can avoid using setters for fields that won't change
public class Book {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long bookId;
  @Embedded
  private Isbn isbn;
  @Embedded
  private Title title;
  @Embedded
  private Author author;
  @Embedded
  private Genre genre;
  @Embedded
  private PublicationYear publicationYear;
  private BigDecimal price;
  // jpa requirement
  public Book() {
  }
  public Book(Isbn isbn, Title title, Author author, Genre genre, PublicationYear publicationYear,
      BigDecimal price) {
    this.isbn = isbn;
    this.title = title;
    this.author = author;
    this.genre = genre;
    this.publicationYear = publicationYear;
    this.price = price;
  }
  public Long getBookId() {
    return bookId;
  }
  public Isbn getIsbn() {
    return isbn;
  }
  public Title getTitle() {
    return title;
  }
  public Author getAuthor() {
    return author;
  }
  public Genre getGenre() {
    return genre;
  }
  public BigDecimal getPrice() {
    return price;
  }
  public PublicationYear getPublicationYear() {
    return publicationYear;
  }
  // setter for price is needed because price of the book can change (discounts and so on)
  public void setPrice(BigDecimal price) {
    this.price = price;
  }
}

这是我的示例值对象 - 所有人都在使用字符串。

   public class Isbn {
  private String isbn;
  // jpa requirement
  public Isbn() {
  }
  public Isbn(String isbn) {
    this.isbn = isbn;
  }
  public String getIsbn() {
    return isbn;
  }
  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    Isbn isbn1 = (Isbn) o;
    return isbn != null ? isbn.equals(isbn1.isbn) : isbn1.isbn == null;
  }
  @Override
  public int hashCode() {
    return isbn != null ? isbn.hashCode() : 0;
  }
  @Override
  public String toString() {
    return "Isbn{" +
        "isbn='" + isbn + ''' +
        '}';
  }
}

是否有一种简单的方法来验证这些对象？如果它是我的实体中的字符串，而不是ISBN对象，我可以使用@pattern与正确的ISBN匹配并使用它。

edit1：也许有一种更好的方法来验证价值对象，而不是一个上方的对象？我有点新的东西，所以想知道是否有更好的选择来验证我的实体。

Answer 1

您可以通过利用@Valid注释来执行Object字段验证;

@Entity
@Access(AccessType.FIELD)
public class Book {
  @Embedded @Valid
  private Isbn isbn;
...
}
public class Isbn {
  @Pattern(//Pattern you'd like to enforce)
  private String isbn;
...
}

然后您可以使用以下内容自己验证;

ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(book);
//if set is empty, validation is OK