登录界面：
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>用户登录</title>
<style type="text/css">
body,td,th {
color: #000;
}
body {
background-color: #0CF;
background-image: url(a.jpg);
}
#form1 blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote p strong {
font-size: 18px;
}
#form1 blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote p strong {
font-size: 9px;
}
#form1 blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote p strong {
font-size: larger;
}
#form1 blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote p strong {
font-size: xx-large;
}
#form1 blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote blockquote p strong {
font-size: x-large;
}
</style>
</head>
<body>
<p><label></label> </p>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<blockquote>
<p align="center"><strong>用户登录（login） </strong></p>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
<p> </p>
<form action="judge.jsp" method="post">
<table width="252" border="1" align="center">
<tr>
<td width="72"><strong>用户名:</strong></td>
<td width="164"><input name="num" type="text" /></td>
</tr>
<tr>
<td><strong>密码:</strong></td>
<td><input name="userpassword" type="password" /></td>
</tr>
<tr>
<td> </td>
<td><a href="judge.jsp" onclick="link"><input type="submit" name="submit" value="登录" ></a></td>
</tr>
</table>
</form>
</body>
</html>
判断并且连接数据库
<%@ page contentType = "text/html; charset=utf-8" import = "java.sql.*" errorPage = "error.jsp" %>
<html>
<head>
</head>
<body>
<div style=text-align:center>
<%
String num = request.getParameter("num");
String userpassword = request.getParameter("userpassword");
if(num=="")
{
out.println("<script language = 'javaScript'> alert('用户名为空，请点击确定重新输入！');</script>");
response.setHeader("refresh","1;url = login.html");
}
else
{
Class.forName("com.mysql.jdbc.Driver");
Connection connect = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/test","root","root");
//连接数据库时,获取一个可以执行sql语句的对象
Statement stmt = connect.createStatement();
String sql = "select * from user where name='"+num+"'and userpassword='"+userpassword+"'";
//用于查询
ResultSet i = stmt.executeQuery(sql);
if(i.next())
{
//定时刷新页面，跳转的目标地址是index1.html
response.setHeader("refresh","1;url = index1.html");
}
else
{
out.println("<script language = 'javaScript'> alert('用户名或密码错误，请点击确定重新输入！');</script>");
response.setHeader("refresh","1;url = login.html");
}
stmt.close();
connect.close();
}
%>
</div>
</body>
<html>
登录成功后的界面
<html>
<!DOCTYPE html>
<html lang="en" class="no-js">
<head>
<meta charset="utf-8">
<title>登录(Login)</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="">
<meta name="author" content="">
<!-- CSS -->
<link rel="stylesheet" href="assets/css/reset.css">
<link rel="stylesheet" href="assets/css/supersized.css">
<link rel="stylesheet" href="assets/css/style.css">
<!-- HTML5 shim, for IE6-8 support of HTML5 elements -->
<!--[if lt IE 9]>
<script src="assets/js/html5.js"></script>
<![endif]-->
</head>
<body>
<div class="page-container">
<h1>恭喜你，登录成功！</h1>
</div>
<!-- Javascript -->
<script src="assets/js/jquery-1.8.2.min.js" ></script>
<script src="assets/js/supersized.3.2.7.min.js" ></script>
<script src="assets/js/supersized-init.js" ></script>
<script src="assets/js/scripts.js" ></script>
</body>
<div style="text-align:center;">
</div>
</html>