spring jpa-必须存在至少一个JPA元模型*

• Z时代
• 2024-01-10
• 分类：问答

有人知道为什么它不起作用吗？

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
06/04/2017 14:11:24.732 ERROR [main] - org.springframework.boot.SpringApplication: Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: At least one JPA metamodel must be present!
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:742)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151)
    at com.cadit.web.WebApplicationAware.main(WebApplicationAware.java:19)
Caused by: java.lang.IllegalArgumentException: At least one JPA metamodel must be present!
    at org.springframework.util.Assert.notEmpty(Assert.java:277)
    at org.springframework.data.jpa.mapping.JpaMetamodelMappingContext.<init>(JpaMetamodelMappingContext.java:52)
    at org.springframework.data.jpa.repository.config.JpaMetamodelMappingContextFactoryBean.createInstance(JpaMetamodelMappingContextFactoryBean.java:71)
    at org.springframework.data.jpa.repository.config.JpaMetamodelMappingContextFactoryBean.createInstance(JpaMetamodelMappingContextFactoryBean.java:26)
    at org.springframework.beans.factory.config.AbstractFactoryBean.afterPropertiesSet(AbstractFactoryBean.java:134)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624)
    ... 16 common frames omitted

我在定义实体com.cadit.entities：

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="TEST")
public class GenericBeans implements BeanType, IEntity<Long> {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "TEST_PAID")
    protected Long id;
    @Column(name = "SOCIETA")
    private String SocietaCod;
    @Column(name = "CONTO_INTERMEDIARIO")
    private String contoInt;
    @Column(name = "TIPO_OPERAZIONE")
    private String tipoOpe;
    public GenericBeans(String societaCod, String contoInt, String tipoOpe) {
        SocietaCod = societaCod;
        this.contoInt = contoInt;
        this.tipoOpe = tipoOpe;
    }
    public GenericBeans() {
    }
    public String getSocietaCod() {
        return SocietaCod;
    }
    public void setSocietaCod(String societaCod) {
        SocietaCod = societaCod;
    }
    public String getContoInt() {
        return contoInt;
    }
    public void setContoInt(String contoInt) {
        this.contoInt = contoInt;
    }
    public String getTipoOpe() {
        return tipoOpe;
    }
    public void setTipoOpe(String tipoOpe) {
        this.tipoOpe = tipoOpe;
    }
    @Override
    public String toString() {
        return "CSV [SocietaCod=" + SocietaCod + ", contoInt=" + contoInt + ", tipoOpe=" + tipoOpe + "]";
    }
    @Override
    public Long getId() {
        return this.id;
    }
    @Override
    public void setId(Long id) {
        this.id=id;     
    }
}

我datasource为spring定义了入口定义：

import org.apache.log4j.Logger;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@ComponentScan
@EntityScan("com.cadit.entities")
//@EnableJpaRepositories("com.cadit.entities")
@EnableTransactionManagement
@PropertySource("classpath:db-config.properties")
public class DbAutoConfiguration {
     static final Logger logger = Logger.getLogger(DbAutoConfiguration.class);
    public DbAutoConfiguration() {
    }
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource(){
        //DataSource ds =new EmbeddedDatabaseBuilder().addScript("classpath:sql/schema.sql").addScript("classpath:testdb/data.sql").build();
        DataSourceBuilder ds =  DataSourceBuilder.create();
        logger.info("dataSource = " + ds);
        return ds.build();
    }
}

我的db-config.properties是：

spring.jpa.hibernate.ddl-auto: validate
spring.jpa.hibernate.naming_strategy: org.hibernate.cfg.ImprovedNamingStrategy
#spring.jpa.database: SQL
spring.jpa.show-sql: true
spring.datasource.driverClassName=net.sourceforge.jtds.jdbc.Driver
spring.datasource.url=jdbc:jtds:sqlserver://localhost:1433;databaseName=example
spring.datasource.username=xxx
spring.datasource.password=xxx

IEntity 是：

public interface IEntity <I extends Serializable> extends Serializable{
/**
  * Property rappresenta la primary key.
  */
  String P_ID = "id";
  /**
   * restituisce la primary key
   * @return
   */
  I getId();
  /**
   * imposta la primary key
   * @param id
   */
  void setId(I id);
}

我尝试使用CrudRepositoryspring的接口将CSV文件写入数据库：

import java.io.File;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.repository.CrudRepository;
import com.cadit.entities.GenericBeans;
import com.csvreader.CsvReader;
public class CsvReaders {
    static final Logger logger = Logger.getLogger(CsvReader.class);
    @Autowired
    public CrudRepository<GenericBeans,Long> _entitymanager;
    public List loadDataFromCsv(String fileName) {
        try {
            File file = new ClassPathResource(fileName).getFile();
            CsvReader csv = new CsvReader(file.getAbsoluteFile().getPath(),';');
            csv.readHeaders();
            List l = new LinkedList();
            GenericBeans b = new GenericBeans ();
            while (csv.readRecord())
            {
                b.setSocietaCod(csv.get(0));
                b.setContoInt(csv.get(1));
                b.setTipoOpe(csv.get(2));
                _entitymanager.save(b); //persist on db
                l.add(b);
                b = new GenericBeans();
            }
            b=null;
            return l;
        } catch (Exception e) {
            logger.error("Error occurred while loading object list from file " + fileName, e);
            return Collections.emptyList();
        }
    }
}

我不使用main类，而是使用扩展的类，SpringBootServletInitializer因为我想在单独的tomcat和Tomcat安装上将其作为WAR应用程序运行

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan(basePackages={"com.cadit.entities","com.cadit.beans"})
@EnableAutoConfiguration
public class WebApplicationAware extends SpringBootServletInitializer {
    private static Class<WebApplicationAware> applicationClass = WebApplicationAware.class;
      public static void main(String[] args) {
            SpringApplication.run(applicationClass, args);
        }
        @Override
        protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
            return application.sources(applicationClass);
        }
}

所有属性文件都在类路径资源中，因为它是一个Maven项目。

pom.xml：

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.springframework</groupId>
    <artifactId>xxxx</artifactId>
    <version>0.1.0</version>
    <packaging>war</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId> 
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.jayway.jsonpath</groupId>
            <artifactId>json-path</artifactId>
            <scope>test</scope>
        </dependency>
       <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.11.1.RELEASE</version>
    </dependency>
    <dependency> 
        <groupId>javax.persistence</groupId> 
        <artifactId>persistence-api</artifactId> 
        <version>1.0.2</version> 
    </dependency>
        <!-- altre dipendenze non spring -->
        <!-- https://mvnrepository.com/artifact/net.sourceforge.javacsv/javacsv -->
        <dependency>
            <groupId>net.sourceforge.javacsv</groupId>
            <artifactId>javacsv</artifactId>
            <version>2.0</version>
        </dependency>
        <!--  per jpa solo se si usa il Tomcat embedded -->
        <dependency>
            <groupId>net.sourceforge.jtds</groupId>
            <artifactId>jtds</artifactId>
            <version>1.3.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-dbcp2</artifactId>
            <version>2.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>
        <!--  end -->
         <!-- dipendenze logback -->
      <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.5</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>1.7.5</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.1.7</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.1.7</version>
        </dependency>
        <!-- fine dip logback -->
    </dependencies>
    <properties>
     <start-class>hello.WebApplicationAware</start-class>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <build>
   <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>
    <repositories>
        <repository>
            <id>spring-releases</id>
            <url>https://repo.spring.io/libs-release</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-releases</id>
            <url>https://repo.spring.io/libs-release</url>
        </pluginRepository>
    </pluginRepositories>
</project>

有什么问题，为什么在运行WebApplicationAware类时找不到JPA实体？

回答：

Spring找不到任何JPA实体，因此没有创建JPA元模型，这就是您要面对异常的原因。

造成此问题的原因可能是您的类路径上的persistence-api版本错误。

您正在使用

<dependency> 
    <groupId>javax.persistence</groupId> 
    <artifactId>persistence-api</artifactId> 
    <version>1.0.2</version> 
</dependency>

但我很确定您的spring版本使用的是persistence-api版本2。

可能是您正在使用版本1中的@Entity注释吗？在运行时，sp​​ring使用版本2，并且仅使用版本2中的@Entity搜索实体！

删除依赖项

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
</dependency>    
<dependency>
   <groupId>org.springframework.data</groupId>
   <artifactId>spring-data-jpa</artifactId>
   <version>1.11.1.RELEASE</version>
</dependency>

而是添加

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

这将为您提供正确版本的所有JPA依赖项。

以上是 spring jpa-必须存在至少一个JPA元模型* 的全部内容， 来源链接： utcz.com/qa/399318.html