Question

I have to create a new cookie if the cookie does not already exist. If the cookie already exist, then I should not override it, but just return it.

How can I verify whether the cookie exists or not? I have looked at javax.servlet.http.Cookie API, but I couldn’t find any clues.

How can I retrieve and validate existing cookies?

Answer 1

You can get all cookies by HttpServletRequest#getCookies().

Cookie[] cookies = request.getCookies();

if (cookies != null) {
    for (Cookie cookie : cookies) {
        String name = cookie.getName();
        String value = cookie.getValue();
        // ...
    }
}

Note that this already contains only valid (non-expired) cookies. The browser namely already won’t send expired cookies along the request.