无法使用JSP设置Cookie

Question

Can't set a cookie through JSP. But JavaScript works good.

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
...//imports and taglibs
<%@ page import="javax.servlet.http.Cookie" %>
<%
    Cookie cookie = new Cookie("testJSP", "testJSP");
    cookie.setMaxAge(365*24*60*60);
    response.addCookie(cookie);
%>
<div ...
   <span><%=request.getCookies()[0].getName() + " " + request.getCookies()[1].getName()%></span>

I will get a JSESSIOID and a name "test" of my cookie that I set through JS, but if I try to add

request.getCookies()[2].getName()

I'll get an "HTTP Status 500 - An exception occurred processing JSP page /WEB-INF/jsp/issueGrid.jsp at line 18" Also in Firebug I don't see cookie that I set from JSP. Can you help me? Where is my problem? Thx!

Answer 1

When doing response.addCookie(cookie); you are actually adding the cookie to the current HTTP response.

To check the cookies defined, try to avoid literal indexes and prefer looping over the list of cookies (or better use jstl c:foreach :

<% for (int i = 0; i < (request.getCookies() != null ? request.getCookies().length : 0); i++) { %>
    <li>
        <%= request.getCookies()[i].getName() + "=" + request.getCookies()[i].getValue()%>
    </li>
<% } %>

BTW if you try to access the cookie (your index 2) you add to the response on the same payload you won't get it, hence a NullPointerException, hence a HTTP 500