【发布时间】：2017-06-05 16:58:16
【问题描述】：
我在我的应用程序中使用 Spring Boot。我有一个访问服务层的控制器，该服务层访问我的 Spring Data JPA 的 CrudRepository 的实现，它与 Hibernate 交互以从数据库中获取数据。 CrudRepository 的以下所有三个实现都返回不正确的对象：
public class ProductRepositoryImpl implements ProductRepository {
@Autowired
private SessionFactory sessionFactory;
@SuppressWarnings("unchecked")
public List<Product> findProductBatch(int start, int end) {
Session session = sessionFactory.getCurrentSession();
Query query = session.createQuery("from Product");
query.setFirstResult(start);
query.setMaxResults(end);
List<Product> list = query.list();
return list;
}
@SuppressWarnings({ "unused", "unchecked" })
@Override
public Iterable<Product> findAll() {
Session session = sessionFactory.getCurrentSession();
List<Product> products = session.createQuery("from Product").list();
Iterable<Product> productIterable = products;
return products;
}
@SuppressWarnings("unchecked")
public List<Product> findBatch(int start, int end) {
Session session = sessionFactory.getCurrentSession();
Query query = session.createQuery("from Product");
query.setFirstResult(start);
query.setMaxResults(end);
List<Product> list = query.list();
return list;
}
}
findOne() 方法仅在传递给它的参数为零且记录的 id 不为零时才返回记录。发送请求时返回以下 JSON 响应：
{
"productId": 0,
"name": "xxxxxx",
"productCategoryId": null,
"created": 1482655958000,
"createdBy": null
}
该记录存在于数据库中，但其 id 为 1，并且确实具有“productCategoryId”，但由于未注入，因此返回 null。
findAll() 方法返回重复多次的同一记录，findBatch() 方法返回类似的响应。
下面是剩下的代码：
Product.java：
@Entity
public class Product {
@Id
private Integer productId;
private String name;
private Integer productCategoryId;
@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "productCategoryId", insertable = false, updatable = false)
@Autowired
private ProductCategory productCategory;
private Date created;
private Integer createdBy;
public Product() {
}
public Product(Integer productId, String name, ProductCategory productCategory, Integer uomId, Date created, Integer createdBy) {
this.productId = productId;
this.name = name;
this.productCategory = productCategory;
this.created = created;
this.createdBy = createdBy;
}
public Product(String name, ProductCategory productCategory) {
this.name = name;
this.productCategory = productCategory;
}
public Integer getProductId() {
return productId;
}
public void setProductId(Integer productId) {
this.productId = productId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getProductCategoryId() {
return productCategoryId;
}
public void setProductCategoryId(Integer productCategoryId) {
this.productCategoryId = productCategoryId;
}
// public ProductCategory getProductCategory() {
// return productCategory;
// }
//
// public void setProductCategory(ProductCategory productCategory) {
// this.productCategory = productCategory;
// }
public Date getCreated() {
return created;
}
public void setCreated(Date created) {
this.created = created;
}
public Integer getCreatedBy() {
return createdBy;
}
public void setCreatedBy(Integer createdBy) {
this.createdBy = createdBy;
}
}
ProductCategory.java：
@Entity
public class ProductCategory {
@Id
private Integer productCategoryId;
private String name;
private Date created;
private Integer createdBy;
public ProductCategory() {
}
public ProductCategory(Integer productCategoryId, String name, Date created, Integer createdBy) {
this.productCategoryId = productCategoryId;
this.name = name;
this.created = created;
this.createdBy = createdBy;
}
public Integer getProductCategoryId() {
return productCategoryId;
}
public void setProductCategoryId(Integer productCategoryId) {
this.productCategoryId = productCategoryId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getCreated() {
return created;
}
public void setCreated(Date created) {
this.created = created;
}
public Integer getCreatedBy() {
return createdBy;
}
public void setCreatedBy(Integer createdBy) {
this.createdBy = createdBy;
}
}
ProductServiceImpl.java
@Service
@Transactional
public class ProductServiceImpl implements ProductService {
@Autowired
private ProductRepository productRepository;
public Product findOne(int productId) {
return productRepository.findOne(productId);
}
public List<Product> findAll() {
List<Product> products = new ArrayList<>();
productRepository.findAll().forEach(products::add);
return products;
}
@Override
public List<Product> findBatch(int start, int end) {
return productRepository.findBatch(start, end);
}
}
ProductController.java：
@RestController
@RequestMapping("/products")
@EnableTransactionManagement
public class ProductController {
@Autowired
private ProductService productService;
@RequestMapping(method = RequestMethod.GET)
public List<Product> findAll() {
List<Product> products = productService.findAll();
return products;
}
@RequestMapping(value = "/{productId}", method = RequestMethod.GET)
public Product findOne(@PathVariable int productId) {
Product product = productService.findOne(productId);
return product;
}
@RequestMapping(value = "/{start}/{end}", method = RequestMethod.GET)
public List<Product> findBatch(@PathVariable int start, @PathVariable int end) {
List<Product> list = productService.findBatch(start, end);
return list;
}
}
ApplicationContextConfig.java：
public class ApplicationContextConfig {
@Bean
public HibernateJpaSessionFactoryBean sessionFactory(EntityManagerFactory emf) {
HibernateJpaSessionFactoryBean factory = new HibernateJpaSessionFactoryBean();
factory.setEntityManagerFactory(emf);
return factory;
}
}
响应还应该包含一个完整注入的 ProductCategory 对象，但它没有。
【问题讨论】：
-
您可能已经检查过了，但这始终是我的第一步：您是否 100% 确定 JPA 连接的数据库是您认为的那样。
-
是的，它正在读取的记录存在于数据库中。
-
我注意到当我更改请求的映射时，findBatch() 方法会从同一个数据库中读取不同的值。即 localhost:8080/0/10 返回与本地主机不同的对象：1/10。他们都返回重复十次的不同记录
-
所以，是的，数据就在那里。只是不正确
-
搞了几天，发现跟Hibernate命名策略有关。通过在 application.properties 中添加以下行，解决了 id 部分：
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
标签： java hibernate spring-mvc spring-boot spring-data-jpa