How to get the session object in general from within a class?

Question

There is a class :

@Configuration
@ComponentScan("com.ambre.pta")
@EnableTransactionManagement
@PropertySources({
    @PropertySource("classpath:fr/global.properties"),
    @PropertySource("classpath:fr/main.properties"),
    @PropertySource("classpath:fr/admin.properties"),
    @PropertySource("classpath:fr/referentiel.properties"),
    @PropertySource("classpath:fr/departement.properties"),
    @PropertySource("classpath:fr/exercice.properties"),
    @PropertySource("classpath:fr/defi.properties")
})
public class ApplicationContextConfig {

    @Bean
    public static PropertySourcesPlaceholderConfigurer properties() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Bean(name = "viewResolver")
    public InternalResourceViewResolver getViewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");
        return viewResolver;
    }

    @Bean(name = "dataSource")
    public DataSource getDataSource() {

        BasicDataSource bds = new BasicDataSource();

        bds.setDriverClassName("oracle.jdbc.driver.OracleDriver");
        bds.setUrl("jdbc:oracle:thin:@localhost:1521:xe");

        bds.setUsername("pta");
        bds.setPassword("pta");

        return bds;

    }

    @Autowired
    @Bean(name = "sessionFactory")
    public SessionFactory getSessionFactory(DataSource dataSource) {

        LocalSessionFactoryBuilder sessionBuilder = new LocalSessionFactoryBuilder(dataSource);

        sessionBuilder.scanPackages("com.ambre.pta.model");

        return sessionBuilder.buildSessionFactory();

    }

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

        HibernateTransactionManager transactionManager = new HibernateTransactionManager(sessionFactory);

        return transactionManager;

    }

    @Autowired
    @Bean(name = "utilisateurDao")
    public UtilisateurDAO getUtilisateurDao(SessionFactory sessionFactory) {
        return new UtilisateurDAOImpl(sessionFactory);
    }

}

We can get the request object within this class by this way :

HttpServletRequest request = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();

So is there a way to get the session ( HttpSession ) object ?

Answer 1

Using Controller classes

You can define HttpSession as an argument to your controller methods:

@RequestMapping("/my-path")
public String doStuff(HttpSession session) {
    // do stuff...
}

This is also the recommended way to access the HttpRequest, rather than going through RequestContextHolder, because it's easier to mock out the session for tests.

See the Spring MVC docs for more detail.

Without using controller classes

Another option is to use a @SessionScope bean and mutate it accordingly:

@Component
@SessionScope
public class MySessionScopedBean {
    String attribute;
}

public class MyOtherClass {
    @Autowired
    private MySessionScopedBean myBean;

    public void doStuff() {
        // myBean accesses a bean instance isolated in the user session
        myBean.attribute = "test";
    }

}

Answer 2

If you want to access the HttpSession outside a Controller method, there are two possible answers:

1. Don't do it, it's evil.

2. If you really really want to do it (and I have done it in the past, so who am I to blame you), then the easiest way is to write a class to hold the session, and an interceptor to set and unset it. But to make things easier, I will be working with HttpServletRequest objects, from which you can extract the session:

   public class RequestHolder {
   
       private static final ThreadLocal<HttpServletRequest> REQUEST =
                                new ThreadLocal<>();
   
       public static HttpServletRequest getCurrentRequest() {
           return REQUEST.get();
       }
   
       public static HttpSession getCurrentSession() {
           HttpServletRequest request = REQUEST.get();
           return request == null ? null : request.getSession();
       }
   
       public static void setCurrentRequest(HttpServletRequest request) {
           REQUEST.set(request);
       }
   
       public static void unsetCurrentRequest() {
           REQUEST.remove();
       }
   
   }
   
   public class RequestHolderInterceptor implements HandlerInterceptor {
       @Override
       public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) {
           RequestHolder.setCurrentRequest(request);
           return true;
       }
   
       @Override
       public void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView mav) {
       }
   
       @Override
       public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object o, Exception e){
           RequestHolder.unsetCurrentRequest();
       }
   }