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Дмитрий
Asked:2020-10-31 02:53:13 +0000 UTC2020-10-31 02:53:13 +0000 UTC

在 Spring Data JPA 中使用 Autowired

  • 772

如何在不从上下文创建服务类实例的情况下使 Autowired 工作？我使用没有 Spring Booth 的 Spring Date。配置类：

@Configuration
@EnableJpaRepositories
public class SpringConfig {

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();

        dataSource.setDriverClassName(com.mysql.jdbc.Driver.class.getName());
        dataSource.setUrl("jdbc:mysql://localhost:3306/kvi?useSSL=false");
        dataSource.setUsername("");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {

        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource());
        entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistenceProvider.class);
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());

        entityManagerFactoryBean.setJpaProperties(hibProperties());
        entityManagerFactoryBean.setPackagesToScan("repository", "models");

        return entityManagerFactoryBean;

    }

    private Properties hibProperties() {
        Properties jpaProperties = new Properties();
        jpaProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
        jpaProperties.setProperty("hibernate.hbm2ddl.auto", "update");

        jpaProperties.setProperty("hibernate.connection.useUnicode", "true");
        jpaProperties.setProperty("hibernate.connection.characterEncoding", "UTF-8");
        return jpaProperties;
    }

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

}

存储库：

@Repository
public interface PersonRepository extends CrudRepository<Person, Long>{
}

这是服务：

@Service
@Transactional
public class PersonService {

    @Autowired
    private PersonRepository personRepository;

    public Iterable<Person> findAll () {
        return personRepository.findAll();
    }
}

好吧，分别有一个 Person 实体（我不会列出）。从主类启动：

@ComponentScan
public class Main {
    public static void main(String[] args) {

        ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        AutowireCapableBeanFactory autowireCapableBeanFactory = context.getAutowireCapableBeanFactory();
        PersonService ps = autowireCapableBeanFactory.createBean(PersonService.class);

        List <Person> pers = new ArrayList <>();
        Iterable<Person> findAll = ps.findAll();
        CollectionUtils.addAll(pers, findAll);
        for (Person p : pers) {
            System.out.println(p);
        }
    }
}

一切都很完美。但问题是每次通过上下文获取服务，如代码( PersonService ps = autowireCapableBeanFactory.createBean(PersonService.class);)所示，说白了就是不方便。

java

2 个回答

  1. 在注释中指定@ComponentScan扫描的基本包@ComponentScan("com.company")。也许 Spring 只是看不到你的课程。

    • 2
  2. Best Answer

    注释@Autowired仅适用于 bean。

    main只有初始化上下文并从中获取“根”bean 才有意义。并在这个 bin 和嵌入其中的 bin 中完成其余的工作。

    @Component
public class Application {
    @Autowired
    private PersonService personService;

    public void start() {
        for (Person p : personService.findAll()) {
            System.out.println(p);
        }        
    }

    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        AutowireCapableBeanFactory autowireCapableBeanFactory = context.getAutowireCapableBeanFactory();
        Application app = autowireCapableBeanFactory.createBean(Application.class);

        app.start();
    }
}
    • 1

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