从ServletContextEvent获取请求标头

Question

我做了一个监听器，它根据set secure flag on cookie programatically在cookie上设置了安全标记 我想像secure flag on session cookies in a java中一样自动启用或禁用此标志 如何从ServletContextEvent获取请求？还有其他方法吗？

public class SecureCookieServletContextListener implements ServletContextListener {
    private static final String LB_HTTPS_HEADER = "Front-End-Https";

    @Override public void contextInitialized(final ServletContextEvent sce) {
        final String httpsHeader = request.getHeader(LB_HTTPS_HEADER);
        boolean secure = httpsHeader != null && httpsHeader.equalsIgnoreCase("on");

        sce.getServletContext().getSessionCookieConfig().setSecure(secure);
    }   
}