package test;import java.sql.*; public class Conn 
{ 
static String data ="jdbc:mysql://localhost/first"; static java.sql.Statement st; public static void databaseconnect() 
{ //函数用于 连接数据库 
try { Class.forName("com.mysql.jdbc.Driver"); Connection conn = DriverManager.getConnection(data, "root", "root"); st = conn.createStatement(); 
} catch (Exception e) { System.out.println("异常："+e.toString()); } } public static String pwquery(String name) {databaseconnect(); String inname = name; String pw = ""; ResultSet rs=null; try { rs = ((java.sql.Statement) st).executeQuery("select * from test2 where name='"+name+"'"); while(rs.next()) { pw=rs.getString("pass"); } rs.close(); st.close(); //pw="abc";} catch (SQLException e) { e.printStackTrace(); } return pw; } 
} 
<?xml version="1.0" encoding="gb2312" ?>
<%@ page language="java" contentType="text/html; charset=gb2312"%>
<%@page import="test.Conn" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><title>test</title></head><body><%
String temp=(String)session.getValue("login"); temp= Conn.pwquery("admin"); // out.print(temp);
out.print(temp);%></body></html>注意把 tomcat\common\lib
添加
mysql-connector-java-5.0.8-bin.jar