Cookie 记录最后访问时间

 package cn.gs.ly.servlet;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.Date;

 import javax.servlet.ServletException;
 import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class LastVisitTimeServlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         resp.setContentType("text/html; charset=UTF-8");        

         PrintWriter out = resp.getWriter();
         out.print("您上次访问的时间是：");
         //先获取cookie  再赋值
         Cookie [] co = req.getCookies();//所有 Cookie 对象的数组
         for(int i=0;co!=null&&i<co.length;i++){ //遍历cookie数组
             if("last_time".equals(co[i].getName())){//获取cookie名
                 String value = co[i].getValue(); //获取cookie值
                 long time = Long.parseLong(value); //转换cookie值类型
                 out.println(new Date(time).toLocaleString());//显示cookie里的最后一次系统时间
             }
         }

         //先查看cookie的最后时间并显示。再获取现在系统当前时间
         long time = System.currentTimeMillis();
         Cookie c = new Cookie("last_time",time+"");//构造带指定名称和值的 cookie。
         c.setMaxAge(30*24*60*60);//cookie存活时间
         c.setPath(req.getContextPath()); //在当前应用有效 s.setPath("/");
         resp.addCookie(c);//添加cookie
     }
     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         this.doPost(req, resp);
     }
 }