验证分两种情况 ，成功，进入管理员页，可以看信息和删记录
失败，直接给出登录失败，然后重新登录
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><%//登录//将号和密码包为user对象 //查user对象是否存在 //如果再切换到管理页//如果不再继续返回login.jsp页 %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录</title>
</head>
<body>
<form action="dologin.jsp" method="post">用户名:<input type="text" name="uname" required="required" size="20" value=""><br>密 码:<input type="password" name="upwd" required="required" size="20"><br><input type="submit" /> <input type="reset" />
</form></body>
</html>dologin.jsp
<%@page import="org.apache.tomcat.dbcp.dbcp2.PStmtKey"%>
<%@page import="java.sql.PreparedStatement"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><%@ page import="
java.util.Date,
java.io.IOException,
java.io.PrintWriter,
java.sql.*
" %><%@ page import="src.User"%><%
//将传过来的信息 包在值类里
User you=new User();//登录的人的信息包装成对象
you.setName(request.getParameter("uname"));
you.setPwd(request.getParameter("upwd"));
%><%//1.导入jar包//2.注册驱动//Class.forName("com.mysql.jdbc.Driver");Class.forName("com.mysql.cj.jdbc.Driver");//3.获取连接Connection con = DriverManager.getConnection("jdbc:mysql://mysql.sqlpub.com:3306/huangjin","laocooon","fc12f7a5215e8e0a");//4.获取执行者对象String sql = "SELECT * FROM adminuser WHERE uname = ?";PreparedStatement pstmt = con.prepareStatement(sql);pstmt.setString(1, you.getName());//给第一个参数为用户名//5.执行sql语句，并且接收结果 ResultSet rs = pstmt.executeQuery();User fUser= new User();//6.遍历记录集while(rs.next()){fUser.setId(rs.getInt(1));fUser.setName(rs.getString(2));fUser.setPwd(rs.getString(3));}// 7 各种关闭rs.close();pstmt.close();con.close();//找到用户名，现在分析密码对不对if(fUser.getPwd().equals(you.getPwd())){//由于 此信息需要整体网站需要，所以使用session处理session.setAttribute("adminuser",fUser);//如果没有找到记录，说明 fUser的id是0if(fUser.getId()==0)response.sendRedirect("./error.html");elseresponse.sendRedirect("./adminuser.jsp"); }elseresponse.sendRedirect("./error.html");%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>验证登录是否成功</title>
</head>
<body></body>
</html>
error.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录失败 </title>
<!--
<style type="text/css">
p{
text-align: center;
font-size: 24px;
color:red;
}</style>--><link href="./css/myCss.css" rel="stylesheet" type="text/css" />
</head>
<body>
<p>登录失败</p>
<p><a href="./login.jsp">重新登录</a></p>
</body>
</html>