这是设置session的代码

<%
    //为first_name和last_name设置cookie
    Cookie firstName = new Cookie("frist_name",request.getParameter("frist_name"));
    Cookie lastName = new Cookie("last_name",request.getParameter("last_name"));

    //设置cookie过期时间为1分钟
    firstName.setMaxAge(60*60*24);
    lastName.setMaxAge(60*60*24);

    //在响应头部添加cookie
    response.addCookie(firstName);
    response.addCookie(lastName);
%> 

#这是删除Cookie的代码

<%
        Cookie cookie = null;
        Cookie[] cookies = null;
        //获取当前Cookies

        cookies = request.getCookies();

        for(int i = 0;i < cookies.length;i++){
            cookie = cookies[i];
            if((cookie.getName()).compareTo("frist_name") == 0){
                cookie.setMaxAge(0);
                cookie.setPath("/");
                response.addCookie(cookie);
                out.print("已删除" + cookie.getName());
            }else{
    %>
                <h1>No found Cookie</h1>            
    <%
            }
        }
    %>

他们不在同一个jsp文件里

http://blog.csdn.net/machinecat0898/article/details/23603493