就是一个jsp登陆页面中，输入用户名和密码，如何连接上数据库并且与数据库中储存的用户名和密码匹配，求助各位大神。
jsp的用户名或者密码，到servlet通过request.getparameter(" xx");获取，通过jdbc存到数据库中。 http://blog.csdn.net/u013829202/article/details/52461437
不就是写jdbc么，百度一大推。
可以尝试通过jdbc连接数据库，并将用户输入的信息与用户的数据库信息进行比较。慕课有关于java的视频教程。
前端校验完成后,ajax发送后台,后台处理与数据库校验
1、将jsp页面的用户名密码传到servlet
2、链接数据库，根据用户名读取当前用户信息；（Java连接数据库读取数据，百度即可）
3、比较传入的密码是否和读取到的用户密码相同；
4、返回结果
直接贴代码吧，写的是有点low，不过还能用用
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" %>
<%@ page import="java.sql.*"%>
<%!
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static final String USER = "root";
public static final String PASS = "123456";
public static final String URL = "jdbc:mysql://localhost/biyesheji?characterEncoding=utf8";
%>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<style type="text/css">
table.hovertable {
font-family: verdana,arial,sans-serif;
font-size:18px;
color:#333333;
border-width: 1px;
border-color: #999999;
border-collapse: collapse;
}
table.hovertable th {
background-color:#c3dde0;
border-width: 1px;
padding: 8px;
border-style: solid;
border-color: #a9c6c9;
}
table.hovertable tr {
background-color:#d4e3e5;
}
table.hovertable td {
border-width: 1px;
padding: 8px;
border-style: solid;
border-color: #a9c6c9;
}
</style>
<!-- PAGE TITLE -->
<title>学生成绩查询</title>
<%@ include file="style.jsp" %>
</head>
<body>
<!-- ===================================
PRELOADER
==================================== -->
<div class="preloader">
<div class="status"></div>
</div>
<!-- ===================================
HEADER
==================================== -->
<header>
<!-- Navigation Menu start-->
<nav class="navbar clean-main-menu" role="navigation">
<div class="container">
<!-- Navbar Toggle -->
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<!-- Logo -->
<a class="navbar-brand" href="index.html"><img style="width:200px" class="logo" id="logo" src="<%=request.getContextPath()%>/images/logo.jpg" alt="Page"></a>
</div>
<!-- Navbar Toggle End -->
<!-- navbar-collapse start-->
<div id="nav-menu" class="navbar-collapse collapse" role="navigation">
<ul class="nav navbar-nav clean-menu-wrapper">
<li>
<a href="<%=request.getContextPath()%>/student">个人中心</a>
</li>
<li>
<a href="<%=request.getContextPath()%>/student/chooseclass">选课管理</a>
</li>
<li class="active">
<a href="<%=request.getContextPath()%>/student/mark">成绩查询</a>
</li>
<li>
<a href="<%=request.getContextPath()%>/student/subject">班级课表</a>
</li>
<li>
<a href="<%=request.getContextPath()%>/student/teache">教师评价</a>
</li>
</ul>
</div>
<%@ page import="java.io.*,java.util.*" %>
<% String username = (String)session.getAttribute("username");%>
<p style="float:right;"><a href="<%=request.getContextPath()%>/login">
<%
if(username != null){
out.print("<a href=\"\">"+username+"</a>"+",<a href=\"/biyesheji/login/logout\">"+"注销</a>");
} else out.print("<a href=\"/biyesheji/login\">【登陆】</a>");
%></p>
</div>
</nav>
<!-- Navigation Menu end-->
</header>
<!-- ===================================
MAIN
==================================== -->
<section id="contact" class="clean-section-wrapper clean-contact-section background-one" data-stellar-background-ratio="0.5">
<div class="clean-parallax-overlay"></div>
<div class="container">
<div class="row">
<!-- Section Header -->
<div class="col-sm-8" style="margin-top: 50px;">
<table class="hovertable">
<tr>
<th>课程代号</th><th>课程名称</th><th>任课教师</th><th>成绩</th>
</tr>
<%
String user = null;
String pass = null;
try{
Class.forName(DRIVER);
Connection con = DriverManager.getConnection(URL,USER,PASS);
String sql = "SELECT * FROM mark WHERE username=\""+username+"\"";
PreparedStatement stat = con.prepareStatement(sql);
ResultSet rs = stat.executeQuery();
while(rs.next()){
String classnumber = rs.getString("classnumber");
String classname = rs.getString("classname");
String teachername = rs.getString("teachername");
int mark = rs.getInt("mark");
int id = rs.getInt("id");
out.println("<tr onmouseover=\"this.style.backgroundColor='#ffff66';\" onmouseout=\"this.style.backgroundColor='#d4e3e5';\">");
out.println("<td>"+classnumber+"</td><td>"+classname+"</td><td>"+teachername+"</td><td>"+mark+"</td>");
out.println("</tr>");
}
con.close();
}
catch(Exception e){
}
%>
</table>
</div>
</div>
</div>
</section>
<!-- ===================================
FOOTER SECTION
==================================== -->
<%@ include file="script.jsp" %>
</body>
</html>
这个需要JDBC、Ajax技术。
输入账号密码后触发JavaScript里的ajax方法，然后到Java后台调用程序，查出和账号匹配的账号、密码。
若数据查不到和账号匹配，直接弹出账号错，
若账号正确，密码不正确，则弹出密码错。
http://blog.csdn.net/null____/article/details/8038359
写一个jdbc和数据库连接，在写dao方法进行账号密码判定最后根据返回的值(true|false)判断账号密码是否正确
连接上数据库并且与数据库中储存的用户名和密码匹配,就是用Java的JDBC操作数据库
可以action到servlet里面连接数据库