登录界面：

find.jsp:

<%@page contentType="text/html"  import ="java.sql.*" pageEncoding="UTF-8"%>

<%

request.setCharacterEncoding("utf-8");

   String id=request.getParameter("id");

   String passwd=request.getParameter("passwd");

   boolean flag=false;

   PreparedStatement sql=null;  

   ResultSet rs=null;

   Connection conn=null;

%>

<% 

            String driverName = "com.mysql.jdbc.Driver";      

            String userName = "root";

            String userPwd = "aaa312";

            String dbName="students";

            String url1 = "jdbc:mysql://localhost:3306/"+dbName;

            String url2="?user="+userName+"&password="+userPwd;

            String url3="&useUnicode=true&characterEncoding=utf-8";

            String url=url1+url2+url3;

            Class.forName(driverName);//加载驱动  

            conn= DriverManager.getConnection(url,userName,userPwd);  

    sql =conn.prepareStatement("select * from students_info where id=? and passwd=?");

    sql.setString(1,id);

    sql.setString(2,passwd);

    rs=sql.executeQuery();

    if (rs.next()) {  

    flag=true;

     }

   rs.close();

   sql.close();

   conn.close();

  %>

<% if(flag==true)

{%>

<% }else response.sendRedirect("f.jsp");%>

s.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

   

    <%String Name=request.getParameter("username");%>

    欢迎你,<%=Name%>成功登录！

f.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

      对不起，你的信息有误，请重新登录！