session和cookie 实现用户登录相应功能

雨点打透心脏的1/2处 2023-09-27 11:31 136阅读 0赞

## 一、需求 ##

1.  用户成功登录后跳转到欢迎界面，欢迎界面有超链接可以再次返回登录界面
2.  从登陆界面跳转到欢迎界面带用户名参数和系统时间
3.  用cookie记录上次访问时间，记录访问次数
4.  用cookie实现两周内免登录

![f35636fb99ad48a185b4bab4fbd5314f.png][]

![75297409611a4a24842c8c8f06a673ba.png][]

![3548c60bf4084b6389ac7f627c042288.png][]

## 二、实现 ##

1.创建登录页面

index.jsp

<title>登入页面</title>
    </head>
    <body>
    <form action="login" method="post">
      用 户 名:<input type="text" name="name" value="${cookie.username.value}"><br>
      密   码:<input type="password" name="password" value="${cookie.password.value}"><br>
      remember：<input type="checkbox" name="remember" value="1"><br><br>
      <input type="submit" value="登录"><br>
      <%
        Date date = new Date();
        out.print("服务器当前时间："+date.toString());
      %>
    </form>
    </body>
    </html>

2.使用HttpServletxxxx对象处理登陆数据

package com.example.demo5;
    
    import javax.servlet.ServletContext;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    @WebServlet(name = "LoginServlet",urlPatterns = {"/login"})
    public class LoginServlet extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            request.setCharacterEncoding("utf-8");
            response.setCharacterEncoding("utf-8");
            response.setContentType("text/html;charset=UTF-8");
    
            String username=request.getParameter("name");
            String password=request.getParameter("password");
            String remember=request.getParameter("remember");
    
            request.getSession().setAttribute("name",username);
    
            HttpSession hs = request.getSession(true);
            hs.setMaxInactiveInterval(20);
            hs.setAttribute("pass","ok");
    
            if(username.equals("中国") && "123".equals(password)){
                HttpSession session = request.getSession();
                session.setAttribute("username",username);
                ServletContext context = request.getServletContext();
    
                if(username.equals("中国") && "123".equals(password)&&"1".equals(remember)){
                    Cookie c_username = new Cookie("username",username);//创建cookie对象用于记录
                    Cookie c_password = new Cookie("password",password);
                    c_username.setMaxAge(14*24*60*60);//保存两周，实现两周内免登录
                    c_password.setMaxAge(14*24*60*60);
                    response.addCookie(c_username);
                    response.addCookie(c_password);
                }
    
                if(context.getAttribute("count")==null){
                    context.setAttribute("count",1);
                }else {
                    context.setAttribute("count",(Integer)context.getAttribute("count")+1);
                }//记录访问次数
                response.sendRedirect("success.jsp?uname="+username);//明文获取用户名
            }else{
                System.out.println("登入失败");
                response.sendRedirect("index.jsp");
            }
        }
    
    }

3.登录成功后的欢迎界面

success.jsp

<%--
      Created by IntelliJ IDEA.
      User: Sangyuan
      Date: 2022/9/25
      Time: 12:52
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page import="java.util.*" %>
    <%@ page import="javax.servlet.http.*"%>
    <%@ page import="java.text.SimpleDateFormat" %>
    <%@ page import="java.net.URLEncoder" %>
    <%@ page import="java.net.URLDecoder" %>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
      <meta http-equiv="refresh" content="1200">
      <title>登录成功</title>
    </head>
    <body>
    <h1>欢迎界面</h1>
    
    <%String name = request.getSession().getAttribute("name").toString();%>
    welcome name=<%=name %><br>
    欢迎你<%=session.getAttribute("name")%><br><br>
    
    网页被访问<%=application.getAttribute("count")%>次
    <%
      HttpSession hs = (HttpSession) request.getSession(true);
      String val = (String)hs.getAttribute("pass");
      if(val == null){
        response.sendRedirect("index.jsp");
      }
    %>
    
    <div class="box"></div>
    <script>
      function getTime() {
        var date = new Date();
        var year = date.getFullYear(); //获取年份
        var month = date.getMonth() + 1; //获取月份
        var day = date.getDate(); //获取日期
        var hour = date.getHours(); //获取小时
        hour = hour < 10 ? '0' + hour : hour;
        var minute = date.getMinutes(); // 获取分
        minute = minute < 10 ? '0' + minute : minute;
        var seconds = date.getSeconds(); //获取秒
        seconds = seconds < 10 ? '0' + seconds : seconds;
        return year + '年' + month + '月' + day + '日 ' + hour + ':' + minute + ':' + seconds;
      }
      setInterval(function() {
        document.querySelector('.box').innerHTML = getTime();
      }, 1000)
    </script><br>
    <%!
      public Cookie isCookieExisted(Cookie[] cookies, String lastTime) {
        Cookie result = null;
        if (cookies != null && cookies.length != 0) {
          for (Cookie cookie : cookies) {
            if (lastTime.equals(cookie.getName())) {
              result = cookie;
              break;
            }
          }
        }
        return result;
      }
    %>
    <%
      Cookie[] cookies = request.getCookies();
      String lastTime = "lastTime";
      Cookie cookie = isCookieExisted(cookies, lastTime); // 判断是否存在lastTime的cookie
      Date date = new Date();
      SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
      String sdfDate = dateFormat.format(date); // 不论是首次还是已经登陆过，都要设置新的时间
      String encode = URLEncoder.encode(sdfDate, "utf-8"); // cookie的值不能含有空格等特殊字符，因此使用url编码
      if (cookie == null) {
        out.write("欢迎您，首次访问");
        cookie = new Cookie(lastTime, encode);
      } else {
        String value = cookie.getValue();
        out.write("上次访问时间：" + URLDecoder.decode(value, "utf-8")); // 因为是url编码，因此需要url解码显示
        cookie.setValue(encode);
      }
      cookie.setMaxAge(14*24*60*60);
      response.addCookie(cookie);
    %>
    
    
    <a href="index.jsp">返回重新登陆</a>
    </body>
    </html>

[f35636fb99ad48a185b4bab4fbd5314f.png]: https://img-blog.csdnimg.cn/f35636fb99ad48a185b4bab4fbd5314f.png
[75297409611a4a24842c8c8f06a673ba.png]: https://img-blog.csdnimg.cn/75297409611a4a24842c8c8f06a673ba.png
[3548c60bf4084b6389ac7f627c042288.png]: https://img-blog.csdnimg.cn/3548c60bf4084b6389ac7f627c042288.png