Filter is not retrieving request.getAttribute()

Question

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    try { 
        String logged = (String) ((HttpServletRequest) request).getAttribute("loginstatus");
        if(logged != null) {
            out.print("ok");
        } else {
            out.print("not ok");
        }

Why is the value of logged always null?

score 4 · Accepted Answer · edited May 23 '17 at 10:33

A filter is by default the very first thing which get executed on a HTTP request. The request attribtues are usually managed by server side code. Who/what should have set the request attribute before this filter does its job?

Aren't you confusing how HTTP requests/responses work? A request get finished/garbaged, including all attributes, when the associated response is finished. Every subsequent request is a brand new one which doesn't contain at all the same attributes as the previous one.

Don't you actually want to use the session scope? Do the following on login:

request.getSession().setAttribute("user", user);

And then the following in authentication filter:

if (((HttpServletRequest).getSession().getAttribute("user") != null) {
    chain.doFilter(request, response); // Continue.
} else {
    ((HttpServletResponse) response).sendRedirect("login"); // Redirect to login.
}

Filter is not retrieving request.getAttribute()

1 Answers1

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