没有可用的“com.example.repo.UserRepository”类型的合格 bean

Question

这是我第一次尝试使用 Spring MVC 使用 Spring Data JPA，但我无法解决此错误。

错误日志

严重：向 org.springframework.web.context.ContextLoaderListener 类的侦听器实例发送上下文初始化事件的异常 org.springframework.beans.factory.UnsatisfiedDependencyException：创建名称为“mainController”的bean时出错：通过字段“userRepository”表示的依赖关系不满足；嵌套异常是 org.springframework.beans.factory.NoSuchBeanDefinitionException：没有“com.example.repo.UserRepository”类型的合格 bean 可用：预计至少有 1 个有资格作为自动装配候选者的 bean。依赖注解：{@org.springframework.beans.factory.annotation.Autowired(required=true)} 在 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) 在 org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) 在 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues（AutowiredAnnotationBeanPostProcessor.java:366） 在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) 在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) 在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) 在 org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) 在 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 在 org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) 在 org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) 在 org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) 在 org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) 在 org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) 在 org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444) 在 org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326) 在 org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107) 在 org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4725) 在 org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5189) 在 org.apache.catalina.util.LifecycleBase.start（LifecycleBase.java:150） 在 org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419) 在 org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409) 在 java.util.concurrent.FutureTask.run(FutureTask.java:266) 在 java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 在 java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 在 java.lang.Thread.run(Thread.java:745) 引起：org.springframework.beans.factory.NoSuchBeanDefinitionException：没有“com.example.repo.UserRepository”类型的合格bean可用：预计至少有1个有资格作为自动装配候选者的bean。依赖注解：{@org.springframework.beans.factory.annotation.Autowired(required=true)} 在 org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1486) 在 org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104) 在 org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) 在 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ... 24 更多

UserRepository.java

 @Repository
 public interface UserRepository extends CrudRepository<User, Integer> {

 }

MainController.java

@Controller
@RequestMapping("/")
public class MainController {

    @Autowired
    private UserRepository userRepository;

    @RequestMapping(value = "/user", method = RequestMethod.POST, headers = "Accept=application/json")
    @ResponseBody
    public ResponseEntity<User> addUser(@RequestBody User user) {
        userRepository.save(user);
        System.out.println("------>>>>>>>>>>" + user.getName());
        HttpHeaders headers = new HttpHeaders();
        return new ResponseEntity<User>(headers, HttpStatus.OK);
    }

    @RequestMapping(value = "/user/list", method = RequestMethod.GET)
    public ResponseEntity<List<User>> listAllUsers() {
        List<User> users = (List<User>)userRepository.findAll();
        if (users.isEmpty()) {
            System.out.println("List is empty oops..!!");
            return new ResponseEntity<List<User>>(HttpStatus.NO_CONTENT);
        }
        System.out.println("Got the List...!!");
        System.out.println("Name of First User---->>>>" + users.get(0).getName());
        return new ResponseEntity<List<User>>(users, HttpStatus.OK);
    }

}

AppConfig.java

@Configuration
@ComponentScan("com.example")
@EnableWebMvc
@EnableJpaRepositories
@EnableTransactionManagement
public class AppConfig {

    @Bean
    public InternalResourceViewResolver viewResolver(){
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();  
        resolver.setPrefix("/WEB-INF");  
        resolver.setSuffix(".html");
        return resolver;  
    }

    @Bean
    public DataSource dataSource(){
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/spring_database");
        dataSource.setUsername("root");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean
    public EntityManagerFactory entityManagerFactory(){
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setShowSql(true);
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan(User.class.getPackage().getName());
        factory.setDataSource(dataSource());
        factory.afterPropertiesSet();
        return factory.getObject();
    }

    @Bean
    public PlatformTransactionManager transactionManager(){
        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory());
        return txManager;
    }

}

User.java

@Entity
@Table(name="user")
public class User {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer id;
    private String name;
    private String email;
    /*Getters and Setters*/

这是我的项目结构

Project Structure

我在这里缺少什么？或者我在这里的错误是什么？谁能解决这个问题？

Answer 1

你需要告诉 spring 在哪里寻找存储库：

@EnableJpaRepositories(basePackageClasses = UserRepository.class)