java - Spring JPA Data Repository 无法为扩展 CrudRepository 的接口(interface)创建 bean

Question

我在使用 Spring JPA 存储库时遇到问题。我创建了:

• 一个基本的用户领域类(@Entity)，
• 一个接口(interface) UserDao 扩展 CrudRepository
• 和服务层实现。

当我运行项目时，由于 UserDao 的 bean 创建异常而失败。据我所知，Spring JPA 存储库负责为此接口(interface)创建 bean(因为它扩展了 CrudRepository)并将其注入(inject)到需要的地方。

这是我遇到的错误:

WARN : org.springframework.web.context.support.AnnotationConfigWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'UserController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private edu.sjsu.services.UserService edu.sjsu.controllers.UserController.userService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userServiceImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: edu.sjsu.models.UserDao edu.sjsu.services.UserServiceImpl.userDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [edu.sjsu.models.UserDao] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)

UserDao.Java:

package edu.sjsu.models;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.CrudRepository;

public interface UserDao extends CrudRepository<User, Long> {}

RootConfig.Java:

@Configuration
@ComponentScan(basePackages={"edu.sjsu"}, excludeFilters={@Filter(type=FilterType.ANNOTATION, value=EnableWebMvc.class)})
@Import(JpaConfig.class)
public class RootConfig {}

JpaConfig.java 我认为如果使用 Spring JPA 我什至不需要它，但我仍然按照指南和教程创建了这个配置类。

@Configuration
@EnableJpaRepositories
@EnableTransactionManagement
public class JpaConfig {

    @Bean
    public DataSource dataSource() {
        EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
        return builder.setType(EmbeddedDatabaseType.HSQL).build();
    }

    @Bean
    public EntityManagerFactory entityManagerFactory() {

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(true);

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan("edu.sjsu");
        factory.setDataSource(dataSource());
        factory.afterPropertiesSet();

        return factory.getObject();
    }

    @Bean
    public PlatformTransactionManager transactionManager() {

        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory());
        return txManager;
    }   

}

如果您需要其他配置和 java 类来了解情况，请告诉我。

Answer 1

在EnableJpaRepositories中使用basePackages:

@Configuration
@EnableJpaRepositories(basePackages = "edu.sjsu.models")
@EnableTransactionManagement
public class JpaConfig { ... }

默认情况下，EnableJpaRepositories会扫描Spring Data repositories注解配置类的包。因为，我猜，你的配置和存储库类在不同的包中，你应该告诉 Spring Data JPA 要扫描哪些基础包以找到 JPA 存储库。