求助：org.hibernate.UnknownEntityTypeException无法定位Product实体

问题描述 #

运行Hibernate测试代码时抛出异常：

org.hibernate.UnknownEntityTypeException: Unable to locate entity descriptor: com.mywebapp.model.Product

原代码与配置 #

Product.java #

@Entity
@Table(name = "product")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "product_name", nullable = false)
    private String productName;
    @Column(name = "sale_price")
    private double salePrice;

    @ManyToOne
    @JoinColumn
    private Order order;

    public Product(String productName, double salePrice) {
        this.productName = productName;
        this.salePrice = salePrice;
    }

    public Product() {
        //Default constructor
    }

    public Long getId() {
        return id;
    }

    public String getProductName() {
        return productName;
    }

    public void setProductName(String name) {
        this.productName = name;
    }

    public double getProductSalePrice() {
        return salePrice;
    }

    public void setProductSalePrice(double salePrice) {
        this.salePrice = salePrice;
    }
}

HibernateTests.java（原代码） #

@SpringBootTest//测试中实体扫描无法找到实体
public class HibernateTests {
    public static void main(String[] args) {
        final StandardServiceRegistry registry = new StandardServiceRegistryBuilder().
                configure()
                .build();

        SessionFactory sessionFactory = new Configuration()
                .configure("hibernate.cfg.xml")
                .buildSessionFactory();
        Session session =sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();

        Product product = new Product();
        product.setProductName("SomeProduct1");
        product.setProductSalePrice(1290.78);
 

        if (Objects.isNull(session.find(Product.class, product.getId()))) {
            session.persist(product);
        } else {
            session.merge(product);
        }
        transaction.commit();
        session.close();
        sessionFactory.close();

    }
}

pom.xml（原配置） #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.bitconex</groupId>
    <artifactId>MyWebApp</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>MyWebApp</name>
    <description>MyWebApp</description>

    <properties>
        <java.version>17</java.version>
        <start-class>src/main/java/com/bitconex/mywebapp/MyWebAppApplication.java</start-class>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>6.2.7.Final</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>

         <dependency>
             <groupId>com.mysql</groupId>
             <artifactId>mysql-connector-j</artifactId>
             <scope>runtime</scope>
         </dependency>

         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
             <exclusions>
                 <exclusion>
                     <groupId>org.junit.vintage</groupId>
                     <artifactId>junit-vintage-engine</artifactId>
                 </exclusion>
             </exclusions>
         </dependency>

         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
         </dependency>

         <dependency>
             <groupId>org.webjars</groupId>
             <artifactId>bootstrap</artifactId>
             <version>5.3.0</version>
         </dependency>

         <dependency>
         <groupId>org.webjars</groupId>
             <artifactId>webjars-locator-core</artifactId>
         </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.6.0</version>
        </dependency>

     </dependencies>

     <build>
         <plugins>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
                 <version>${project.parent.version}</version>
             </plugin>

         </plugins>
     </build>

 </project>

application.properties（原配置） #

#H2 Database Configuration
spring.datasource.url=jdbc:postgresql://localhost:5432/CatalogProDB
spring.datasource.driver-class-name=org.postgresql.Driver
spring.datasource.username=postgres
spring.datasource.password=password

#Hibernate Configuration for PostgreSQL
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.show_sql=true

server.port=8081

问题原因 #

1. 测试类混用原生Hibernate API与Spring Boot环境：标注@SpringBootTest的类中使用原生Hibernate的Configuration和SessionFactory构建方式，绕过了Spring Boot的JPA自动配置，导致实体扫描机制失效。
2. 实体包路径未被扫描：Product类所在的com.mywebapp.model包不在Spring Boot主类（com.bitconex.mywebapp）的默认扫描范围内，Spring无法识别该实体。
3. 重复依赖冲突：spring-boot-starter-data-jpa已包含兼容版本的Hibernate核心依赖，手动添加hibernate-core可能引发版本冲突。

解决方案 #

1. 修正测试类，使用Spring Boot的JPA支持 #

删除原生Hibernate的SessionFactory构建代码，注入Spring管理的EntityManager：

@SpringBootTest
@Transactional
public class HibernateTests {

    @PersistenceContext
    private EntityManager entityManager;

    @Test
    public void testProductPersistence() {
        Product product = new Product();
        product.setProductName("SomeProduct1");
        product.setProductSalePrice(1290.78);

        // 持久化实体
        entityManager.persist(product);
        entityManager.flush();

        // 验证实体是否存在
        Product savedProduct = entityManager.find(Product.class, product.getId());
        Assertions.assertNotNull(savedProduct);
        Assertions.assertEquals("SomeProduct1", savedProduct.getProductName());
    }
}

2. 确保实体包被Spring扫描 #

在Spring Boot主类上添加@EntityScan指定实体包路径：

@SpringBootApplication
@EntityScan("com.mywebapp.model") // 扫描指定包下的实体类
public class MyWebAppApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyWebAppApplication.class, args);
    }
}

3. 清理重复依赖 #

删除pom.xml中的hibernate-core依赖，保留spring-boot-starter-data-jpa即可：

<!-- 移除该依赖 -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>6.2.7.Final</version>
</dependency>

4. 移除不必要的数据库驱动 #

当前使用PostgreSQL，可移除H2和MySQL驱动依赖：

<!-- 移除H2驱动 -->
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>

<!-- 移除MySQL驱动 -->
<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <scope>runtime</scope>
</dependency>

补充说明 #

如果一定要使用原生Hibernate API，需在hibernate.cfg.xml中显式注册实体类：

<hibernate-configuration>
    <session-factory>
        <!-- 其他配置 -->
        <mapping class="com.mywebapp.model.Product"/>
    </session-factory>
</hibernate-configuration>

但Spring Boot项目中推荐使用Spring提供的JPA集成，更符合生态最佳实践。

内容的提问来源于stack exchange，提问作者user22566443