请高手给查个关于Cookie的错
<%@ page language="java" import="javax.servlet.http.Cookie,java.util.*" pageEncoding="UTF-8"%>
......
<body>
<%
String userName="cookietest";
//通u-28729 request对u-29599 将ookie中u30340 内u23481 读u20986
Cookie[] cookie=request.getCookies();
Cookie cookie_response=null;
List list=Arrays.asList(cookie);
Iterator it=list.iterator();
while(it.hasNext())
{
Cookie temp=(Cookie)it.next();
if(temp.getName().equals(userName+"_access_time"))
{
cookie_response=temp;
break;
}
}
out.println("当前时间"+new Date()+"<br>");
if(cookie_response!=null)
{
out.println("上次时间"+cookie_response.getValue());
cookie_response.setValue(new Date().toString());
}
else
{
cookie_response=new Cookie(userName+"_access_time",new Date().toString());
}
response.addCookie(cookie_response);
response.setContentType("text/html");
response.flushBuffer();
%>
</body>
</html>
出现下面错误信息，由于本人刚刚接触JSP对于此类信息不能正确分析，望各位高手指点!!
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.NullPointerException
java.util.Arrays$ArrayList.<init>(Arrays.java:2355)
java.util.Arrays.asList(Arrays.java:2341)
org.apache.jsp.response.responseCookie_jsp._jspService(responseCookie_jsp.java:79)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
[2431 byte] By [goldennut] at [2008-1-6] 