//記錄電腦上次打開網(wǎng)頁的時(shí)間
 
@WebServlet("/CookieTest")
public class CookieTest extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //設(shè)置響應(yīng)體格式與編碼
        resp.setContentType("text/html;charset=utf-8");
        //獲取cookie
        Cookie[] cookies = req.getCookies();
        boolean flag=false;
        //遍歷cookie數(shù)據(jù)
        if (cookies!=null && cookies.length>0){
            for (Cookie cookie : cookies) {
                String name = cookie.getName();
                //判斷名稱中是否有:lastTime
                if ("lastTime".equals(name)){
                    //設(shè)置Cookie的value，下一次使用
                    flag=true;
                    Date date=new Date();
                    SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
                    String str_date = sdf.format(date);
                    //tomcat不支持特殊字符，需要通過URL編碼
                    System.out.println("編碼前 "+str_date);
                    str_date=URLEncoder.encode(str_date,"utf-8");
                    System.out.println("編碼后"+str_date);
 
                    //新值串回去，設(shè)置存活時(shí)間
                    cookie.setValue(str_date);
                    cookie.setMaxAge(60*60*24);
                    resp.addCookie(cookie);
                    //有，歡迎光臨，上次登錄時(shí)間
                    String value = cookie.getValue();
                    //URL 解碼
                    value=URLDecoder.decode(value,"utf-8");
                    resp.getWriter().write("<h1>歡迎回來，您上一次的訪問時(shí)間是:"+value+"</h1>");
                    break;
                }
            }
        }
        if (cookies==null || cookies.length==0 || flag==false){
            //第一次訪問
            Date date=new Date();
            SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
            String str_date = sdf.format(date);
 
            //tomcat不支持特殊字符，需要通過URL編碼
            System.out.println("編碼前 "+str_date);
            str_date=URLEncoder.encode(str_date,"utf-8");
            System.out.println("編碼后"+str_date);
 
            Cookie cookie=new Cookie("lastTime",str_date);
            //新值串回去，設(shè)置存活時(shí)間
            cookie.setValue(str_date);
            cookie.setMaxAge(60*60*24);
            resp.addCookie(cookie);
 
            resp.getWriter().write("<h1>您好，歡迎您首次訪問</h1>");
        }
 
    }
  }

@WebServlet("/SessionDemo1")
public class SessionDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //session
        HttpSession session = request.getSession();
        session.setAttribute("msg","hello session");
        //請求轉(zhuǎn)發(fā)(這個(gè)是在一個(gè)URL中)
        request.setAttribute("reqmsg","hello req.session");
        request.getRequestDispatcher("/SessionDemo3").forward(request,response);
 
 
    }
 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request,response);
    }
}
 
 
@WebServlet("/SessionDemo3")
public class SessionDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       //獲取數(shù)據(jù)
        HttpSession session = request.getSession();
        Object msg = session.getAttribute("msg");
        System.out.println(msg);
        //請求轉(zhuǎn)發(fā)
        Object reqmsg = request.getAttribute("reqmsg");
        System.out.println(reqmsg);
    }
 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request,response);
    }
}