@Autowired SessionFactory 在 Java 配置中返回 null spring

Question

I m having null pointer exception in sessionFactory when i try to use DI in sessionFactory I have to turn spring 3 project into Spring 4 with no xml. I dont know what the problem im facing, SessionFactory doesnot autowired at all. when i try to test case generic doa Add Method

here is my Configuration File for bean

@Configuration
@EnableTransactionManagement
@EnableWebMvc
@ComponentScan(basePackages = "io.github.bibekshakya35.ehealth")
public class EhealthCofiguration {

@Bean
public ViewResolver getViewResolver() {
    InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
    viewResolver.setViewClass(JstlView.class);
    viewResolver.setPrefix("/WEB-INF/view/");
    viewResolver.setSuffix(".jsp");
    return viewResolver;
}

@Bean(name = "dataSource")
public javax.sql.DataSource getDataSource() {
    BasicDataSource dataSource = new BasicDataSource();
    dataSource.setDriverClassName("org.postgresql.Driver");
    dataSource.setUrl("jdbc:postgresql://localhost:5432/ehealth");
    dataSource.setUsername("test");
    dataSource.setPassword("test123");
    return dataSource;
}

@Autowired
@Bean(name = "sessionFactory")
public SessionFactory getSessionFactory(javax.sql.DataSource dataSource) {
    LocalSessionFactoryBuilder sessionBuilder = new LocalSessionFactoryBuilder(dataSource);
    sessionBuilder.scanPackages("io.github.bibekshakya35.ehealth.model");
    sessionBuilder.addProperties(getHibernateProperties());
    return sessionBuilder.buildSessionFactory();
}

private Properties getHibernateProperties() {
    Properties properties = new Properties();
    properties.put("hibernate.show_sql", "true");
    properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
    properties.put("hibernate.hbm2ddl.auto", "update");
    return properties;
}

@Autowired
@Bean(name = "transactionManager")
public HibernateTransactionManager getTransactionManager(
        SessionFactory sessionFactory) {
    HibernateTransactionManager transactionManager = new HibernateTransactionManager(
            sessionFactory);

    return transactionManager;
}
}

to load this class i have created

public class EhealthWebAppIntializer implements WebApplicationInitializer {

@Override
public void onStartup(ServletContext servletContext) throws ServletException {
    AnnotationConfigWebApplicationContext applicationContext = new AnnotationConfigWebApplicationContext();
    applicationContext.register(EhealthCofiguration.class);
    ServletRegistration.Dynamic dispatcher =servletContext.addServlet("SpringDispatcher", new DispatcherServlet(applicationContext));
    dispatcher.setLoadOnStartup(1);
    dispatcher.addMapping("/");
}

}

this is my generic doa class where im injecting SessionFactory when it try to access sessionFactory.getCurrentSession(); NPE is occur,

@Repository
@Transactional
public class HibernateDAO<T extends Serializable> implements IGenericDao<T> {

private Class<T> clazz;

Session session;

@Autowired
SessionFactory sessionFactory;

private static final Logger LOG = Logger.getLogger(HibernateDAO.class.getName());

@Override
public void setClazz(Class<T> clazzToSet) {
    this.clazz = clazzToSet;
}

@Override
public void create(T entity) {
    session = getCurrentSession();
    LOG.log(Level.INFO, "inside create entity and you just bind your session to the current one{0}", session.toString());
    session.saveOrUpdate(entity);
    LOG.info("saved");
    session.flush();
    session.refresh(entity);
}



protected Session getCurrentSession() {
    return sessionFactory.getCurrentSession();
}  
}

Here is my stack trace for NPE

Exception in thread "main" java.lang.NullPointerException
at io.github.bibekshakya35.ehealth.DAO.genericdao.HibernateDAO.getCurrentSession(HibernateDAO.java:115)
at io.github.bibekshakya35.ehealth.DAO.genericdao.HibernateDAO.create(HibernateDAO.java:85)
at io.github.bibekshakya35.ehealth.service.impl.user.main(user.java:46)

here is my user entity

@Entity
@Table(name = "users")
public class User implements Serializable, AbstractEntity {


@Id
@Column(name = "username",unique = true)
private String userName;

@NotNull(message = "password cannot be empty")
@Column(name = "users_password")
private String userPassword;

@Embedded
private UserProfile userProfile;

@Embedded
private AuditInfo auditInfo;

@Enumerated(EnumType.STRING)
private UserType userType;

@Column(name = "is_active")
private boolean active = true;

//getter n setter

}

Answer 1

In chat, You provided me with this code :

 public static void main(String[] args) {
     User user = new User();
     IGenericDao<User> iGenericDao = new HibernateDAO<>();
     user.setUserName("bibekshakya35");
     user.setUserPassword("ros3");
     user.setUserType(UserType.GUEST);
     user.setActive(true);
     UserProfile userProfile = new UserProfile();
     userProfile.setAge(21);
     userProfile.setBasicInfo("kdhsa");
     userProfile.setEmailId("dsadas@gmail.com");
     userProfile.setUserGender(UserGender.Male);
     userProfile.setFullname("bibek shakya");
     userProfile.setMobileNumber("45454545");
     userProfile.setLandLineNumber("445444");
     userProfile.setUserProfilePic("index.jsp");
     user.setUserProfile(userProfile);
     AuditInfo auditInfo = new AuditInfo();
     auditInfo.setCreatedOn(new Date());
     auditInfo.setModifiedOn(new Date());
     auditInfo.setVerifiedOn(new Date());
     user.setAuditInfo(auditInfo);
     iGenericDao.create(user);
   }

As You are creating the new HibernateDAO instance like this
IGenericDao<User> iGenericDao = new HibernateDAO<>();
This is creating the problem.

In the case where You are using annotations, creating new instance manually ,usually causes the above mentioned error.

Spring can only autowire beans that it manages; if you call new to create a bean yourself, @Autowired fields don't get filled in (and methods like @PostConstruct aren't called).

You need to add @autowired to the HibernateDAO which will instantiate it with the exact class which includes the real @Autowired SessionFactory.

:
Usually we do it in the class which is itself annotated with annotations like @Controller or @Service .
Like this

@Controller
@RequestMapping(value="/someURL")
public class mainClass {
    @Autowired
    HibernateDAO abc;
    //Code (methods) to test Your CRUD Operations
}