Question

This question is related to another one that I posted recently: Understanding HttpServletRequest and cookies in JSF .

In order to implement a Remember Me login in JSF, I am using a cookie and reading it in WebFilter. The filter gets the cookie and sets the cookie value in the SessionScoped ManagedBean, but for some reason the ManagedBean isn’t able to display it in the web page.

Filter’s doFilter implementation:

@Override
public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain)
        throws IOException, ServletException {

    HttpServletRequest req = (HttpServletRequest) request;
    Cookie[] cookies = req.getCookies();
    if (cookies != null) {
        for (Cookie cookie : cookies) {
            if (cookie.getName().equals("MyTestCookie")) {
                System.out.println("Filter got cookie: " + cookie.getValue());
                cookieBean.setValue(cookie.getValue());
            }
        }
    }
    chain.doFilter(request, response);
}

CookieBean class:

@ManagedBean
@SessionScoped
public class CookieBean implements Serializable {

    private String value;

    @PostConstruct
    public void init() {
        System.out.println("Instantiated CookieBean");
    }

    public String getValue() {
        System.out.println("CookieBean returning Value: " + value);
        return value;
    }

    public void setValue(String value) {
        System.out.println("CookieBean getting Value: " + value);
        this.value = value;
    }

    public void create() {
        ExternalContext ec = FacesContext.getCurrentInstance().getExternalContext();
        Map<String, Object> props = new HashMap<String, Object>();
        props.put("maxAge", 10000);
        ec.addResponseCookie("MyTestCookie", "Hello Cookie", props);
    }    
}

CookieBean cookieBean is injected into the filter by means of javax.inject.Inject annotation.

Body of index.xhtml:

<h:form>
    <h:commandButton value="Create Cookie!" action="#{cookieBean.create()}" >
        <f:ajax render="@form" />
    </h:commandButton>
    <p></p>
    <h:outputText value="Cookie value: #{cookieBean.value}" /> 
</h:form>

The first problem is that, after setting the cookie, if I start a new session (by opening a new browser session), the web page isn’t aware of the cookie value, because the SessionScoped ManagedBean is updated after the page is displayed.

Question 1: how can I detect the cookie value in time to update some rendered attribute in the web page?

The second problem is that, if I reload the web page by pressing the reload (or refresh) button in the browser, the ManagedBean instance is the same as before (the @PostConstruct method isn’t fired), but the web page shows a null cookie value and the same is shown in the server’s output:

CookieBean returning Value: null
Filter got cookie: Hello Cookie
CookieBean getting Value: Hello Cookie

Question 2: how is it possible that a SessionScoped ManagedBean loses its property without being re-created?

Answer 1

Answer to Question 1: as explained in the accepted answer for this question, I simply had to do a redirect in the backing bean. This forces JSF to produce a new GET request with the cookie in. Supposing that the requesting page was my welcome page, I had to write this in my cookieBean:

FacesContext.getCurrentInstance().getExternalContext().redirect("faces/index.xhtml");

Well, this works nicely, but the complete URL is now shown in the address bar. I’ll investigate further if there is a way for avoiding this.

Answer to Question 2: the SessionScoped cookieBean was effectively instantiated twice, one during deployment, and one by the filter. The problem is that I was using a JSF ManagedBean and injecting it with javax.inject.Inject annotation. I have made it a CDI Bean by means of javax.inject.Named and javax.enterprise.context.SessionScoped annotations, and the injection is now working well.