工程文件目录：
user数据库的login表：
代码：
login.jsp:
<%@ page contentType="text/html; charset=gb2312" pageEncoding="UTF-8"%> <html> <head> <title>用户登录</title> </head> <body> <h2 align="center">用户登录</h2> <form name="form1" action="login_process.jsp" method="post" onsubmit="return isValidate(form1)"> <table align="center" border="0"> <tr> <td>账号：</td> <td><input type="text" name="username"></td> </tr> <tr> <td>密码：</td> <td><input type="password" name="password"> </td> </tr> <tr> <td></td> <td><input type="submit" value="登录"></td> </tr> </table> </form> </body> </html>
login_process.jsp:
<%@ page language="java" import="java.sql.*" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>登录中</title> </head> <body> <% request.setCharacterEncoding("UTF-8"); String driverStr = "com.microsoft.sqlserver.jdbc.SQLServerDriver"; String connStr = "jdbc:sqlserver://localhost:1433; DatabaseName=user"; String dbusername = "sa"; String dbpassword = "4980"; Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; Class.forName(driverStr); conn = DriverManager.getConnection(connStr, dbusername, dbpassword); String sql = "select * from login where [username]=? and [password]=?";//定义一个查询语句 stmt = conn.prepareStatement(sql); String user=(String)request.getParameter("username"); String pass=(String)request.getParameter("password");//取出login.jsp的值 stmt.setString(1, user); stmt.setString(2, pass); if(user.equals("")) { out.print("<script language='javaScript'> alert('账号为空');</script>"); response.setHeader("refresh", "0;url=login.jsp"); } else if(pass.equals("")) { out.print("<script language='javaScript'> alert('密码为空');</script>"); response.setHeader("refresh", "0;url=login.jsp"); } rs = stmt.executeQuery(); if(rs.next()) response.sendRedirect("login_success.jsp"); else { out.print("<script language='javaScript'> alert('账号或密码错误');</script>"); response.setHeader("refresh", "0;url=login.jsp"); } stmt.close(); conn.close(); %> </body> </html>
代码运行结果：