用户登录案例
login.jsp中写提交表单
s1.jsp和s2.jsp为受限页面
AServlet处理数据
类User内存储了若干账号，密码
1.首先login.jsp提交登录数据到ASevlet中
2.Aservlet获取到用户名和密码，用request.getParameter()方法
3.然后把User类中用map存的用户名和密码拿出来和表单数据进行比较
4.比较
若用户名匹配到
-----比较密码
----------密码相同，把用户名密码保存到session域中，把用户名保存到cookie中，重定向到s1.jsp
----------密码不同，把密码错误信息储存到request域中，请求转发到login.jsp,
若用户名匹配不到
-----把用户名不存在错误信息储存到request域中，请求转发到login.jsp,
5.login.jsp页面获取cookie显示到页面中
6.s1.jsp和s2.jsp获取session域中的username,若为空，把请登录错误信息储存到request域中，请求转发到login.jsp,
User类
package cn.hpu.user;
import java.util.HashMap;
import java.util.Map;
public class User {
public static Map<String,String> findUser(){
Map<String,String> map = new HashMap<String, String>();
map.put("1234567", "1234567");
map.put("2345678", "2345678");
map.put("3456789", "3456789");
return map;
}
}
login.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%>">
<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">
-->
</head>
<body>
<%
String user = "";
Cookie[] c = request.getCookies();
for(Cookie c1:c){
if(c!=null&&c1.getName().equals("uname")){
user += c1.getValue();
}
}
%>
<%
String s1 = "";
String s2 = (String)request.getAttribute("elem");
if(s2!=null){
s1+=s2;
}
%>
<font color="red"><b><%=s1%></b></font>
<form action="/day11_01/BServlet" method="post">
用户名：<input type="text" name="username" value="<%=user%>"/><br/>
密码：<input type="password" name="password"/><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
BServlet
package cn.hpu.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.validator.constraints.Length;
import cn.hpu.user.User;
public class BServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获取表单数据
String username = request.getParameter("username");
String password = request.getParameter("password");
/*
* 校验用户名密码
* 由于没有学数据库，我把用户名密码存到了map集合中
*
* */
//得到所有用户数据
Map<String,String> map = User.findUser();
int size = map.size();
int k = 0;
//遍历map集合中的用户名密码
Set<Entry<String,String>> set = map.entrySet();
for (Entry<String, String> en : set) {
k++;
System.out.println(en.getValue()+":"+username);
if(en.getKey().equals(username)){//找到了用户名，匹配密码
if(en.getValue().equals(password)){//密码匹配成功，重定向到s1.jsp
//把用户名信息保存到Cookie中
Cookie c1 = new Cookie("uname", username);
c1.setMaxAge(60*60*24*30);
response.addCookie(c1);
//保存用户信息到 session域中
request.getSession().setAttribute("username", username);
request.getSession().setAttribute("password", password);
//重定向
response.sendRedirect("/day11_01/login/s1.jsp");
break;
}else{
//错误信息请求转发到登录页面
request.setAttribute("elem", "密码错误");
request.getRequestDispatcher("/login/login.jsp").forward(request, response);
System.out.println("密码错误！");
break;
}
}else if(k==size){
//错误信息请求转发到登录页面
request.setAttribute("elem", "用户名不存在");
request.getRequestDispatcher("/login/login.jsp").forward(request, response);
System.out.println("用户名不存在!");
// System.out.println(en.getKey());
// System.out.println(username);
break;
}
}
}
}
s1.jsp
<body>
<%
String username = (String)session.getAttribute("username");
if(username==null){
request.setAttribute("elem", "请登录！");
request.getRequestDispatcher("/login/login.jsp").forward(request, response);
return;
}
%>
<a>欢迎参观本页面1</a>
<a href="/day11_01/login/s2.jsp">下一页</a>
</body>
s2.jsp
<body>
<%
String username = (String)session.getAttribute("username");
if(username==null){
request.setAttribute("elem", "请登录！");
request.getRequestDispatcher("/login/login.jsp").forward(request, response);
return;
}
%>
<a>欢迎参观本页面2</a>
</body>