Saving and using a cookie with CDI - jsf

Question

I am trying to save a Cookie upon user request, and to later use that cookie to fill in a text field. I am using Java CDI and a login bean. I am new to all three. For online resources all I can find is
#Inject #CookieParam
private String username;
and
#Inject #CookieParam("username")
private Instance<String> usernameResolver;
...
String username = usernameResolver.get();
For the first one the error message says " Unsatisfied dependencies for type [String] with qualifiers [#Default]"
For the second one the only error I get says "Failed to start context"
How should I fix this problem?
Thanks

Answer 1

As the #CookieParam package name hints, this is specific to JAX-RS, Java EE's other framefork for RESTful web services. This would only work in a JAX-RS managed resource as annotated by #Path. This won't work in a JSF or CDI managed bean as annotated by #ManagedBean or #Named.
If you're using JSF's #ManagedBean to manage the bean, then it's available by EL-evaluating #{cookie.username} as #ManagedProperty.
#ManagedBean
public class Bean {
#ManagedProperty("#{cookie.username}")
private String username;
// ...
}
If you're using CDI's #Named to manage the bean, then you've resort to either a custom annotation, or grabbing it as Cookie from the current FacesContext. As the former is not trivial (but actually a nice idea for OmniFaces though), I'll show only the latter:
#Named
public class Bean {
private String username;
#PostConstruct
public void init() {
Cookie cookie = (Cookie) FacesContext.getCurrentInstance().getExternalContext().getRequestCookieMap().get("username");
if (cookie != null) {
username = cookie.getValue();
}
}
// ...
}
Then, in order to save it, the only way is using ExternalContext#addResponseCookie().
FacesContext.getCurrentInstance().getExternalContext().addResponseCookie("username", username, properties);
Don't forget to take into account that a cookie value is very restrictive as to allowed characters. You might want to URL-encode and -decode it upon save and retrieval. JSF utility library OmniFaces offers helper methods which do that implicitly.
username = Faces.getRequestCookie("username");
Faces.addResponseCookie("username", username, -1);
Unrelated to the concrete problem, storing something sensitive like "user name" as a cookie is scary. Are you aware that cookies are manipulatable by the enduser? That the person who's visiting your webpage can easily edit a cookie value representing an "user name" to that of someone else?