通过index.jsp输入用户名、密码登录，跳转到check.jsp验证用户名、密码；
在Check.jsp中，访问数据库 login ，查看输入的用户名、密码是否在数据库中匹配。
注意：这里使用的是Oracle数据库，要将Oracle的驱动放入项目指定目录，如图：
Index.jsp配置如下：
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html> 4 <html> 5 <head> 6 <meta charset="UTF-8"> 7 <title>Insert title here</title> 8 </head> 9 <body> 10 <form action="check.jsp"> 11 用户名：<input type="text" name="uname" ><br> 12 密码：<input type="password" name="upwd" ><br> 13 <input type="submit" value="登录" ><br> 14 15 </form> 16 </body> 17 </html>
Check.jsp配置如下：
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!-- 注意JSP中import的写法 --> 4 <%@ page import="java.sql.*" import="java.io.IOException"%> 5 <!DOCTYPE html> 6 <html> 7 <head> 8 <meta charset="UTF-8"> 9 <title>Insert title here</title> 10 </head> 11 <body> 12 <% 13 String URL = "jdbc:oracle:thin:@localhost:1521:ORCL"; 14 String USERNAME = "scott"; 15 String PWD = "tiger"; 16 try { 17 Class.forName("oracle.jdbc.OracleDriver"); 18 } catch (ClassNotFoundException e) { 19 // TODO Auto-generated catch block 20 e.printStackTrace(); 21 } 22 // 与数据库建立连接 23 try (Connection connection = DriverManager.getConnection(URL, USERNAME, PWD);) { 24 String sql = "select count(*) from login where name=? and pwd=?"; 25 PreparedStatement pstmt = connection.prepareStatement(sql); //预编译 26 27 String name = request.getParameter("uname"); 28 String pwd = request.getParameter("upwd"); 29 30 pstmt.setString(1, name); 31 pstmt.setString(2, pwd); 32 ResultSet rs = pstmt.executeQuery(); 33 34 int count = -1; 35 if (rs.next()) { 36 count = rs.getInt(1); 37 } 38 if (count > 0) { 39 out.println("登陆成功！"); 40 } else { 41 out.println("登陆失败"); 42 } 43 44 } catch (SQLException e) { 45 // TODO Auto-generated catch block 46 e.printStackTrace(); 47 } 48 %> 49 </body> 50 </html>
原文：https://www.cnblogs.com/gilgamesh-hjb/p/12313203.html