1.安装MySQL数据库，建立用户表 uid uname upwd 并插入3条数据
2.制作jsp登录页面 login.jsp 提交到dologin.jsp，使用jdbc连数据库，判断输入的用户名密码是否存在
3.如果存在，把用户名保存在SESSION中，跳转到welcome.jsp，welcome.jsp中读取session中的用户名，显示欢迎你xxx
4.若不存在，跳到登录页面。
<%@ page contentType="text/html;charset=UTF-8" language="java"%>
<html>
<head>
<title>登陆界面</title>
<link rel="stylesheet" href="./layui/css/layui.css">
<link rel="stylesheet" href="./css/adminLogin.css">
</head>
<body>
<div class="wrap">
<img src="img/1.jpg" class="imgStyle">
<div class="loginForm">
<form action="get.jsp" method="POST">
<div class="logoHead"></div>
<div class="usernameWrapDiv">
<div class="usernameLabel">
<label>用户名:</label>
</div>
<div class="usernameDiv">
<i class="layui-icon layui-icon-username adminIcon"></i> <input
id="loginUsername" class="layui-input adminInput" type="text"
name="name" placeholder="输入用户名">
</div>
</div>
<div class="usernameWrapDiv">
<div class="usernameLabel">
<label>密码:</label>
</div>
<div class="passwordDiv">
<i class="layui-icon layui-icon-password adminIcon"></i> <input
id="loginPassword" class="layui-input adminInput" type="password"
name="password" placeholder="输入密码">
</div>
</div>
<div class="usernameWrapDiv">
<div class="usernameLabel">
<label>验证码:</label>
</div>
<div class="cardDiv">
<input id="loginCard" class="layui-input cardInput" type="text"
name="card" placeholder="输入验证码">
</div>
<div id="code_box" class="codeDiv">xxxx</div>
</div>
<div class="usernameWrapDiv">
<div class="submitLabel">
<label>没有账号？<a href="#" id="loginRegister">点击注册</a> </label>
</div>
<div class="submitDiv">
<input id="loginBtn" type="submit"
class="submit layui-btn layui-btn-primary" value="登录"></input>
</div>
</div>
</form>
</div>
</div>
<script>
var code_box = document.getElementById("code_box");
function refreshCode() {
var code = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM', char = '', result = '';
for ( var i = 0; i < 4; i++) {
var code_index = Math.round(Math.random() * 61);
var char = code[code_index];
if (result.toUpperCase().indexOf(char.toUpperCase()) > -1)
{
i--;
continue;
}
result += char;
}
code_box.innerHTML = result;
}
code_box.onclick = refreshCode;
</script>
<%
String name="";
if(!session.isNew()){
name=(String)session.getAttribute("name");
if (name==null){
name="";
}
}
%>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java"%>
<%@ page language="java" import="java.util.*"%>
<%@ page import="java.sql.*"%>
<html>
<head>
<title></title>
</head>
<body>
<%--<%--%>
<%-- String name=request.getParameter("name");--%>
<%-- String password=request.getParameter("password");--%>
<%-- if(name.equals("zs")&&password.equals("123")){--%>
<%--%><p>welcome<%=name%></p><%--%>
<%--}else{--%>
<%--%><p>登陆失败</p><%--%>
<%-- }--%>
<%--%>--%>
<%
PreparedStatement pre = null;
Statement sql;
ResultSet rs;
request.setCharacterEncoding("utf-8");
String Name = request.getParameter("name");
String Ps = request.getParameter("password");
Name.trim();
Ps.trim();
request.setCharacterEncoding("utf-8");
Class.forName("com.mysql.cj.jdbc.Driver");
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/jsp_db?serverTimezone=GMT",
"root", "135790");
sql = conn.createStatement();
String SQL = "select * from jsp_data where uname=? and upassword=?";
pre = conn.prepareStatement(SQL);
pre.setString(1, Name);
pre.setString(2, Ps);
rs = pre.executeQuery();
if (rs.next()) {
String name = rs.getString(1);
session.setAttribute("name", name);
%><p>
欢迎登陆：<%=name%></p>
<%
} else {
%>
<p>输入错误，请重新登录</p>
<a href="index.jsp"><button>返回登录界面</button>
</a>
<%
}
rs.close();
sql.close();
conn.close();
%>
</body>
</html>