自动装配仅在某些组件

Question

在其他地方，所有@Autowired things都可以正常工作（dao中的services，service中的controller，但在一个组件中则不然。 service package有Abstract class和package实施。内部实现类@Autowired service为空，但@Autowired service中的controller工作正常。

对于测试，我将class与Abstract class分开，但问题并没有消失。始终创建所有bean。

package com.mp3.tagger.service.middleware;

    @Component(value = "localMatadataMiddleware")
    public class LocalMatadataMiddleware extends Middleware/*Abstract class*/ {

        @Autowired
        private ArtistService artistService;

        @Override
        public Artist findMetadata(String artistName, String trackName) {
            List<Artist> artist = artistService.findAll();//is null

            //another code...
        }
    } 

配置：

@Configuration
@EnableTransactionManagement
@PropertySource({ "classpath:persistence-mysql.properties" })
@ComponentScan({ "com.mp3.tagger" })
@EnableJpaRepositories(basePackages = "com.mp3.tagger.persistence.dao")
public class PersistenceJPAConfig {

    @Autowired
    private Environment env;

    public PersistenceJPAConfig() {
        super();
    }

    // beans

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        final LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource());
        em.setPackagesToScan(new String[] { "com.mp3.tagger.persistence.entity" });

        final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaProperties(additionalProperties());

        return em;
    }

    @Bean
    public DataSource dataSource() {
        final DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(Preconditions.checkNotNull(env.getProperty("jdbc.driverClassName")));
        dataSource.setUrl(Preconditions.checkNotNull(env.getProperty("jdbc.url")));
        dataSource.setUsername(Preconditions.checkNotNull(env.getProperty("jdbc.user")));
        dataSource.setPassword(Preconditions.checkNotNull(env.getProperty("jdbc.pass")));

        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(final EntityManagerFactory emf) {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        return transactionManager;
    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
        return new PersistenceExceptionTranslationPostProcessor();
    }

    final Properties additionalProperties() {
        final Properties hibernateProperties = new Properties();
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));
        hibernateProperties.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));
        hibernateProperties.setProperty("hibernate.cache.use_second_level_cache", env.getProperty("hibernate.cache.use_second_level_cache"));
        hibernateProperties.setProperty("hibernate.cache.use_query_cache", env.getProperty("hibernate.cache.use_query_cache"));
        // hibernateProperties.setProperty("hibernate.globally_quoted_identifiers", "true");
        return hibernateProperties;
    }

我使用Intellij Idea 2017.3.3

UPD：

我尝试实施模式 - 责任链并创建实例

Middleware middleware = new LocalMatadataMiddleware();
middleware.findMetadata("Radiohead", "Fake Plastic Trees");

抽象类：

public abstract class Middleware {

    private Middleware next;

    public Middleware linkWith(Middleware next) {
        this.next = next;
        return next;
    }

        //Main executable method of chain of responsibility
    public abstract Artist findMetadata(String artistName, String songName);

    public boolean checkIsCorrectAnswer(Artist artist, String artistName, String songName) {
        if (artist.getName().equals(artistName) || artist.getTrack().stream().anyMatch(e -> e.getTitle().equals(songName))) {
            return true;
        }
        return false;
    }

    protected Artist checkNext(String artistName, String songName) {
        if (next == null) {
            return new Artist();
        }
        return next.findMetadata(artistName, songName);
    }
}

服务：

@Service
@Transactional
public class ArtistService {

    @Autowired
    private ArtistDao artistDao;

    public ArtistService() {
        super();
    }

    public void createArtist(final Artist entity){
        artistDao.create(entity);
    }

    public void updateArtist(Artist entity){
        artistDao.update(entity);
    }

    public Artist findOne(long id){
        return artistDao.findOne(id);
    }

    public List<Artist> findAll(){
        return artistDao.findAll();
    }

    public Artist findTrackById(long id){
        return artistDao.findOne(id);
    }

    public void delete(Artist entity){
        artistDao.delete(entity);
    }

    public void deleteById(long id){
        artistDao.deleteById(id);
    }
}