jsp清空cookie

<%@page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String appname = "";//应用service名称
try{
appname = request.getParameter("appname");
}catch(Exception e){

}

if("1".equals(appname)){
out.println("appname="+appname+"<br>");
//存储cookie
Cookie cookie = new Cookie("appname",appname);
cookie.setPath(request.getContextPath());
cookie.setMaxAge(-1);
response.addCookie(cookie);
out.println("存储cookie成功<br>");
}
if("2".equals(appname)){
out.println("appname="+appname+"<br>");
//清空cookie中的appname
Cookie killMyCookie = new Cookie("appname", null);
killMyCookie.setMaxAge(0);
killMyCookie.setPath(request.getContextPath());
response.addCookie(killMyCookie);
out.println("清空cookie成功<br>");
}
%>