Question

I have an old project that I need to integrate with Spring 2.5.x (3.0 is not possible).

I have created a bean, that have to initializate its field userSession by itself:

public class SomeBean {
    UserSession userSession;

    @PostContrust
    public void init() {
        HttpSession session = WebContext.current().getSession();
        userSession = (UserSession) session.getAttribute("userSession");
    }
}

Is it possible to write some kind of autowiring handler that will resolve userSession and pass it for autowiring to Spring, so my bean looks just like:

public class SomeBean {
    @Autowire UserSession userSession;
}

and the handler like:

public class AutowireHanlder {
    public boolean isCandidate(Class<?> type) {
        return type.equals(UserSession.class);
    }

    public Object resolve(Class<?> type) {
        HttpSession session = WebContext.current().getSession();
        return (UserSession) session.getAttribute("userSession");
    }
}

Answer 1

I would do this using a session-scoped FactoryBean:

public class UserSessionFactoryBean extends AbstractFactoryBean<UserSession> {

    @Override
    public Class<?> getObjectType() {
        return UserSession.class;
    }

    @Override
    protected UserSession createInstance() throws Exception {
        HttpSession session = WebContext.current().getSession();
        return (UserSession) session.getAttribute("userSession");   
    }

}

Define UserSessionFactoryBean as a bean:

<bean scope="session" class="com.xyz.UserSessionFactoryBean"/>

… and then you should then be able to autowire UserSession into any other bean.

The complexity here is that UserSessionFactoryBean has to be session-scoped (see docs on bean scopes), since it must return a new value for each HttpSession. This means that any bean it is autowired into must also be session-scoped, otherwise it’ll fail. You can get around this restriction using scoped-proxies.