设置cookie

public class CookieUtils {    /**     * Return a cookie given a particular key     *     * @param httpServletRequest Request     * @param cookieKey Cookie key     * @return <code>Cookie</code> of the requested key or <code>null</code> if no cookie     * under that name is found     */    public static Cookie getCookie(HttpServletRequest httpServletRequest, String cookieKey) {        Cookie[] cookies = httpServletRequest.getCookies();        if (cookies == null) {            return null;        }        for (int i = 0; i < cookies.length; i++) {            Cookie cookie = cookies[i];            if (cookie.getName().equals(cookieKey)) {                return cookie;            }        }        return null;    }    /**     * Add a cookie with a key and value to the response     *     * @param httpServletResponse Response     * @param cookieKey Cookie key     * @param cookieValue Cookie value     */    public static void addCookie(HttpServletResponse httpServletResponse,                                 int cookieExpiration,                                 String cookieKey,                                 String cookieValue) {        Cookie cookie = new Cookie(cookieKey, cookieValue);        cookie.setPath("/");   //这行比较重要，设置路径，不能没有        cookie.setMaxAge(cookieExpiration);        httpServletResponse.addCookie(cookie);    }}