java - 仅当通过 JAX-RS 调用时才出现 Hibernate 错误

Question

我正在尝试创建一个项目，使用 Jersey 作为 JAX-RS 引用实现，使用 Hibernate 作为 JPA 引用实现。项目分为 2 个模块:projectWeb 和 projectJPA。

在projectJPA中，我有树类: CityServiceTest.java、CityService.java 和 City.java

在projectWeb中我有一个类: CityServiceImpl.java

CityServiceTest.java:

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.TypedQuery;

public class CityServiceTest {
    public static EntityManagerFactory ENTITY_MANAGER_FACTORY = Persistence.createEntityManagerFactory("NepremicnineDM");

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        getCities();
    }

    public static void getCities() {
        EntityManager em = ENTITY_MANAGER_FACTORY.createEntityManager();
        String strQuery = "SELECT c FROM City c WHERE c.id IS NOT NULL";
        TypedQuery<City> tq = em.createQuery(strQuery, City.class);
        List<City> cities = tq.getResultList();
        for(City city : cities) {
            System.out.print(city);
        }
    }
}

当我将其作为 Java 应用程序运行时，一切正常，城市会像这样打印在控制台中: 城市 [id=1，name=喀 boolean ，cCode=AFG]城市 [id=2，name=Qandahar，cCode=AFG]城市 [id=3，name=赫拉特，cCode=AFG]，...

当我尝试从 ProjectWeb、CityServiceImpl 类调用 CityService 类时出现问题。 CityService 类与 CityServiceTest 类非常相似。

城市服务类:

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.TypedQuery;

public class CityService {
    public static EntityManagerFactory ENTITY_MANAGER_FACTORY = Persistence.createEntityManagerFactory("NepremicnineDM");

    public List<City> getCities() {
        EntityManager em = ENTITY_MANAGER_FACTORY.createEntityManager();
        String strQuery = "SELECT c FROM City c WHERE c.id IS NOT NULL";
        TypedQuery<City> tq = em.createQuery(strQuery, City.class);
        List<City> cities = tq.getResultList();
        return cities;
    }
}

CityServiceImpl 类:

import java.util.List;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import com.NepremicnineJPA.City;
import com.NepremicnineJPA.CityService;

@Path("city")
public class CityServiceImpl {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<City> getApp() {
        CityService cs = new CityService();
        ...

城市类别:

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
 @Entity
    @Table(name = "city")
    public class City implements Serializable {

        private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "ID", unique = true)
    private int id;
    @Column(name = "Name")
    private String name;
    @Column(name = "CountryCode")
    private String cCode;
    ...

ProjectJPA pom 片段:

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.19</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.4.1.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>5.4.1.Final</version>
    </dependency>* 

ProjectWeb pom 片段:

    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet-core</artifactId>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.inject</groupId>
        <artifactId>jersey-hk2</artifactId>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-binding</artifactId>
    </dependency>        
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.19</version>
    </dependency>

因此，当我尝试通过 projectWeb 调用它时，Wildfly 给了我一个错误:

javax.servlet.ServletException: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: City is not mapped [SELECT c FROM City c WHERE c.id IS NOT NULL] at deployment.NepremicnineDM.ear.NepremicnineDMWeb.war//org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:410) at deployment.NepremicnineDM.ear.NepremicnineDMWeb.war//org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:346) at deployment.NepremicnineDM.ear.NepremicnineDMWeb.war//org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:366) at deployment.NepremicnineDM.ear.NepremicnineDMWeb.war//org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:319) at deployment.NepremicnineDM.ear.NepremicnineDMWeb.war//org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205) at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74) ...

有人可以帮我吗？ P.S.:我知道类似的话题已经被回答过很多次了，但我找不到对我有用的答案。谢谢。

编辑:persistence.xml 文件

<persistence-unit name="NepremicnineDM" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

    <class>com.NepremicnineDMJPA.NepremicnineDM.City</class>
    <properties>
        <property name="javax.persistence.jdbc.driver" 
        value="com.mysql.jdbc.Driver"></property>
        <property name="javax.persistence.jdbc.url" 
        value="jdbc:mysql://localhost/world"></property>
        <property name="javax.persistence.jdbc.user" 
        value="root"></property>
        <property name="javax.persistence.jdbc.password" 
        value="root"></property>
    </properties>
</persistence-unit>

Answer 1

问题似乎是您没有为 City 类定义任何映射。仅当您将总体框架设置为在 Java 类中查找注释时，才将其标记为 @Entity 才有效。如果您使用 Spring Boot 之类的东西来运行您的应用程序，那就没问题。但是，如果您只是直接从命令行运行它，则需要编写大量配置代码才能将应用程序指向实体。在 Hibernate 的早期版本中，这是通过 EntityManager 引用的单独 XML 文件来完成的。