How to parse a cookie string

Question

I would like to take a Cookie string (as it might be returned in a Set-Cookie header) and be able to easily modify parts of it, specifically the expiration date.

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Answer 1

Funny enough, but java.net.HttpCookie class cannot parse cookie strings with domain and/or path parts that this exact java.net.HttpCookie class has converted to strings.

For example:

HttpCookie newCookie = new HttpCookie("cookieName", "cookieValue");
newCookie.setDomain("cookieDomain.com");
newCookie.setPath("/");

As this class implements neither Serializable nor Parcelable, it's tempting to store cookies as strings. So you write something like:

saveMyCookieAsString(newCookie.toString());

This statement will save the cookie in the following format:

cookieName="cookieValue";$Path="/";$Domain="cookiedomain.com"

And then you want to restore this cookie, so you get the string:

String cookieAsString = restoreMyCookieString();

and try to parse it:

List cookiesList = HttpCookie.parse(cookieAsString);
StringBuilder myCookieAsStringNow = new StringBuilder();
for(HttpCookie httpCookie: cookiesList) {
    myCookieAsStringNow.append(httpCookie.toString());
}

now myCookieAsStringNow.toString(); produces

cookieName=cookieValue

Domain and path parts are just gone. The reason: parse method is case sensitive to words like "domain" and "path".
Possible workaround: provide another toString() method like:

public static String httpCookieToString(HttpCookie httpCookie) {
    StringBuilder result = new StringBuilder()
            .append(httpCookie.getName())
            .append("=")
            .append("\"")
            .append(httpCookie.getValue())
            .append("\"");

    if(!TextUtils.isEmpty(httpCookie.getDomain())) {
        result.append("; domain=")
                .append(httpCookie.getDomain());
    }
    if(!TextUtils.isEmpty(httpCookie.getPath())){
        result.append("; path=")
                .append(httpCookie.getPath());
    }

    return result.toString();
}

I find it funny (especially, for classes like java.net.HttpCookie which are aimed to be used by a lot and lot of people) and I hope it will be useful for someone.