jsp实现用户自动登录功能

2020-06-01 23:18:14

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理解并掌握Cookie的作用以及利用cookie实现用户的自动登录功能，实现下图效果

当服务器判断出该用户是首次登录的时候，会自动跳转到登录界面等待用户登录，并填入相关信息。通过设置Cookie的有效期限来保存用户的信息，关闭浏览器后，验证是否能够自动登录，若能登录，则打印欢迎信息；否则跳转到登录页面。

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><%request.setCharacterEncoding("GB2312"); %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" >  <title>My JSP 'login.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0">  <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" > --> <script type="text/javascript"> window.onload = function(){  //获取submit  var submit = document.getElementById("submit");  var name = document.getElementById("name");  //为submit绑定单击响应函数  submit.onclick = function(){    times = document.getElementsByName("time");  var count=0;  for(var i=0;i<times.length;i++){   if(times[i].checked == true){   count++;   }  }  if(count>=2){   alert("只能选择一个选项");   return false;  }    };    };  </script> </head>  <body> <!-- 设置html页面 --> <form action="sucess.jsp" method="post"> 用户名：<input name="username" /><br/>  <input type="checkbox" name="time" value="notSave" />不保存  <input type="checkbox" name="time" value="aDay" />一天  <input type="checkbox" name="time" value="aWeek" />一周  <input type="checkbox" name="time" value="forever" />永久  <br/><br/>  <input type="submit" name="submit" id="submit" value="登录"/> </form> <%  //读取session值 String val= (String)session.getAttribute("name"); //如果session不存在 if(val==null){  val ="不存在"; } out.print("当前/""+val+"/"用户可自动登录"); %>    </body></html>

sucess.jsp

%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" >  <title>My JSP 'show.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0">  <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" > --> </head>  <body> <% //获取username String name = request.getParameter("username"); //判断用户名是否存在 if(name != null && !name.trim().equals("")){  String[] time = request.getParameterValues("time"); //设置session值，便于login页面读取 session.setAttribute("name", name); //设置Cookie Cookie Cookie = new Cookie("name",name); //根据提交选项设置cookie保存时间 if(time != null){  for(int i=0;i<time.length;i++){  //不保存Cookie  if(time[i].equals("notSave")){   Cookie.setMaxAge(0);   }  //保存一天Cookie  if(time[i].equals("aDay")){   Cookie.setMaxAge(60*60*24);  }  //保存一周Cookie  if(time[i].equals("aWeek")){   Cookie.setMaxAge(60*60*24*7);  }  //永久保存Cookie，设置为100年  if(time[i].equals("forever")){   Cookie.setMaxAge(60*60*24*365*100);  }  } }    //在客户端保存Cookie response.addCookie(Cookie); }  else{%>  <%--用户名不存在则进行判断是否已有cookie --%> <% //获取cookie Cookie[] cookies = request.getCookies();  //cookie存在 if(cookies != null && cookies.length > 0){  for(Cookie cookie:cookies){  //获取cookie的名字  String cookieName = cookie.getName();  //判断是否与name相等  if(cookieName.equals("name")){   //获取cookie的值   String value = cookie.getValue();   name = value;   }  }  } } if(name != null && !name.trim().equals("")){ out.print("您好: " + name+"欢迎登录"); } else{//否则重定向到登录界面  out.print("您还没有注册，2秒后转到注册界面！"); response.setHeader("refresh","2;url=login.jsp"); %> 如果没有自动跳转，请点击<a href="login.jsp" rel="external nofollow" >此处</a>进行跳转 <% //response.sendRedirect("login.jsp"); }%>   </body></html>

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