Hibernate 命名实体的自动映射

Question

在我当前的 Spring Boot REST 示例项目中，我有两个实体( Book 和 BookSummary )，均由 PagingAndSortingRepository 提供。 。 Book实体如下所示:

@Entity(name = "Book")
public class Book
{
    @Id
    @GeneratedValue(generator = "UUID")
    @GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
    private UUID uuid;

    private String title;

    private String author;

    private String publisher;

    @Transient
    private String type = "Book";

    ...[Getter & Setter]...
}

BookSummary实体如下所示:

@Entity(name = "Book")
public class BookSummary
{
    @Id
    @GeneratedValue(generator = "UUID")
    @GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
    private UUID uuid;

    private String title;

    private String author;

    @Transient
    private String type = "BookSummary";

    ...[Getter & Setter]...
}

PagingAndSortingRepository实体如下所示:

@Repository
public interface BookRepository extends PagingAndSortingRepository<Book, UUID>
{
    Page<Book> findAll(Pageable pageable);
}

BooksRestController实体如下所示:

@RestController
@RequestMapping("/books")
public class BooksRestController
{
    @GetMapping("/{uuid}")
    public Book read(@PathVariable UUID uuid)
    {
        return bookRepository.findOne(uuid);
    }

    @GetMapping
    public Page<Book> read(Pageable pageable)
    {
        return bookRepository.findAll(pageable);
    }

    @Autowired
    private BookRepository bookRepository;
}

关于PagingAndSortingRepository和 BooksController实现时，我假设 REST 服务将提供 Book 的集合通过 /books 的实体路线。然而，该路线提供了 BookSummary 的集合。实体:

{
    content: [
        {
            uuid: "41fb943e-fad4-11e7-8c3f-9a214cf093ae",
            title: "Some Title",
            author: "Some Guy",
            type: "BookSummary"
        },
        ...
    ]
}

books/41fb943e-fad4-11e7-8c3f-9a214cf093ae然而路线提供了 Book摘要(如预期):

{
    uuid: "41fb943e-fad4-11e7-8c3f-9a214cf093ae",
    title: "Some Title",
    author: "Some Guy",
    publisher: "stackoverflow.com"
    type: "Book"
}

有人可以帮助我理解 Hibernate 的以下行为吗？

Answer 1

我猜 Hibernate 会感到困惑，因为您通过使用以下注释来命名两个具有相同实体名称的实体类:

@Entity(name = "Book")

在这种情况下，您应该简单地使用@Entity并让Hibernate使用实体类的非限定名称。

为每个实体创建一个存储库也是一种很好的做法:一个用于 Book 实体，第二个用于 BookSummary 实体。我不得不说，我从未见过 Spring Data 存储库用于两个不同的实体。无论如何，您的 Controller 逻辑可能如下:

@RestController
@RequestMapping("/books")
public class BooksRestController
{
    private final BookRepository bookRepository;
    private final BookSummaryRepository bookSummaryRepository;

    @Autowired
    public BooksRestController(BookRepository bookRepository, BookSummaryRepository bookSummaryRepository)
    {
        this.bookRepository = bookRepository;
        this.bookSummaryRepository = bookSummaryRepository;
    }

    @GetMapping("/{uuid}")
    public BookSummary read(@PathVariable UUID uuid)
    {
        return bookSummaryRepository.findOne(uuid);
    }

    @GetMapping
    public Page<Book> read(Pageable pageable)
    {
        return bookRepository.findAll(pageable);
    }
}