必须至少存在一个JPA元模型！但它是生成的

Question

我目前正在尝试为Spring+JPA+Hibernate创建一个Spring最小示例。

我创建了以下类：

AppConfig.class

package test;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
@Configuration
@ComponentScan(basePackageClasses = AppConfig.class)
@EnableJpaRepositories(basePackageClasses = Employee.class)
public class AppConfig {
}

AppMain.class

package test;
import java.util.List;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;

public class AppMain {
    public static void main(String args[]) {
        AbstractApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
        EmployeeRepository service = (EmployeeRepository) context.getBean("AccountRepository");
        /*
         * Create Employee1
         */
        Employee employee1 = new Employee();
        employee1.setName("name1");
        /*
         * Create Employee2
         */
        Employee employee2 = new Employee();
        employee2.setName("name2");
        /*
         * Persist both Employees
         */
        service.save(employee1);
        service.save(employee2);
        List<Employee> emps = service.findAll();
        for (Employee emp : emps) {
            System.out.println(emp);
        }
        context.close();
    }
}

Empoyee.class

package test;

import java.io.Serializable;
import java.util.Objects;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "EMPLOYEE")
public class Employee implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @Column(name = "NAME", nullable = false)
    private String name;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "Employee{" + "id=" + id + ", name=" + name + '}';
    }
    @Override
    public int hashCode() {
        int hash = 5;
        hash = 19 * hash + this.id;
        hash = 19 * hash + Objects.hashCode(this.name);
        return hash;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Employee other = (Employee) obj;
        if (this.id != other.id) {
            return false;
        }
        if (!Objects.equals(this.name, other.name)) {
            return false;
        }
        return true;
    }
}

存储库

package test;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
    Employee findOneByName(String name);
    List<Employee> findAllByOrderByIdAsc();
}

Hibernate配置

package test;
import java.util.Properties;
import javax.sql.DataSource;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateTransactionManager;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
@PropertySource(value = {"classpath:application.properties"})
public class HibernateConfiguration {
    @Autowired
    private Environment environment;
    @Bean
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(dataSource());
        sessionFactory.setPackagesToScan(new String[]{"test"});
        sessionFactory.setHibernateProperties(hibernateProperties());
        return sessionFactory;
    }
    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driverClassName"));
        dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
        dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
        dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));
        return dataSource;
    }
    private Properties hibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));
        properties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));
        properties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));
        properties.put("hibernate.hbm2ddl.auto", "update");
        return properties;
    }
    @Bean
    @Autowired
    public HibernateTransactionManager transactionManager(SessionFactory s) {
        HibernateTransactionManager txManager = new HibernateTransactionManager();
        txManager.setSessionFactory(s);
        return txManager;
    }
}

application.properties

jdbc.driverClassName = org.h2.Driver
jdbc.url = jdbc:h2:./test
jdbc.username = myuser
jdbc.password = mypassword
hibernate.dialect = org.hibernate.dialect.H2Dialect
hibernate.show_sql = false
hibernate.format_sql = false

最后是pom.xml

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.websystique.spring</groupId>
    <artifactId>Spring4HibernateExample</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>
    <name>Spring4HibernateExample</name>
    <properties>
        <springframework.version>4.0.6.RELEASE</springframework.version>
        <hibernate.version>4.3.6.Final</hibernate.version>
        <mysql.version>5.1.31</mysql.version>
        <joda-time.version>2.3</joda-time.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.10.1.RELEASE</version>
        </dependency>
        <!-- Hibernate -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-jpamodelgen</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.1-api</artifactId>
            <version>1.0.0.Final</version>
        </dependency>       
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.191</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>eclipselink</artifactId>
            <version>2.5.2</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

如果我试着运行这个例子，我会得到：…由以下原因引起：java.lang.IollegalArgumentException：必须至少存在一个JPA元模型！

但我可以在目标文件夹中看到自动生成的元模型文件。我错过了什么

Answer 1

值得一提的是，当我尝试使用hibernate entitymanager版本5.2.1.Final通过spring boot starter数据jpa 1.3.0.RELEASE.进行spring boot时，我看到了相同的错误消息

我也看到了在目标/生成的源/注释中生成的MetaModel对象。

使用旧的4.3.11.最终版本运行良好-没有错误。对我来说，这看起来像是spring-boot和hibernate版本之间的版本不兼容，也许这很有帮助。