用Jsp做的一个简单的登陆界面，连接Mysql，数据库名字为school，表为user。
主要分为四个Jsp界面：index.jsp登陆界面，check.jsp检验页面，main.jsp登陆成功界面，error.jsp登陆失败界面。
如下所示：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>登陆界面</title>
</head>
<body>
<br><br><br><br><br><br><br><br>
<center>
<form action="check.jsp" method="post">
<table width="380" border="2" bgcolor="#95BDFF" >
<tr>
<td><br><h1> 欢迎光临，请登陆</h1></td>
</tr>
<tr>
<td>
<br> 用户名字 :
<input name="username" type="text" size="28">
<br><br>
用户密码 :
<input name="userpass" type="password" size="29" >
<br><br>
<input type="submit" name="submit" value="提交" style="height:30px;width:80px">
<input type="reset" name="reset" value="取消" style="height:30px;width:80px">
<br>
</td>
</tr>
</table>
</form>
</center>
</body>
</html><%@ page language="java" import="java.sql.*" pageEncoding="utf-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;UTF-8">
<title>登陆界面</title>
</head>
<body>
<%
String username = new String(request.getParameter("username").getBytes("ISO-8859-1"),"utf-8");
String password = new String(request.getParameter("userpass").getBytes("ISO-8859-1"),"utf-8");
session.setAttribute("name",username);
Connection dbconn = null;
Statement stmt = null;
ResultSet rs = null;
if(username.equals("")){
response.sendRedirect("index.jsp");
}
try{
String driver = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql://localhost:3306/school";
String user = "sa";
String Password = "123";
Class.forName(driver);
dbconn = DriverManager.getConnection(url, user, Password);
stmt = dbconn.createStatement();
String sql1 = "select * from user where username='"+username+"'";
rs = stmt.executeQuery(sql1);
if(rs.next()){
//String sql2 = "select * from user where password='"+password+"'";
//rs = stmt.executeQuery(sql2);
//判断用户密码是否正确
String userpass = rs.getString("password");
if(userpass.equals(password)){
response.sendRedirect("main.jsp");
}
else{
response.sendRedirect("error.jsp");
}
}
else{
response.sendRedirect("error.jsp");
}
}catch(Exception e){
e.printStackTrace();
}
finally{
rs.close();
stmt.close();
dbconn.close();
}
%>
</body>
</html>
<%@ page language="java" import="java.util.*" import="java.text.*" pageEncoding="utf-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>登陆成功界面</title>
</head>
<body>
<h1>登陆成功，<%=session.getAttribute("name")%>欢迎您！</h1>
<%
Date now = new Date();
DateFormat mediumDateFormat = DateFormat.getDateTimeInstance( DateFormat.MEDIUM, DateFormat.MEDIUM);
%>
<h2> <%out.println(mediumDateFormat.format(now));%></h2>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>登陆失败界面</title>
</head>
<body>
<h1>登陆失败，您输入的用户名或者密码不正确！</h1>
</body>
</html>
