以Tomcat 5.5 ，Mysql 5.0为例说明
1 在tomcat的admin页面中设置Data Source
JNDI Name：TEST
Data Source URL：jdbc:mysql://localhost:3306/test
JDBC Driver Class: com.mysql.jdbc.Driver
User Name: test <!--数据库的用户名，密码-->
Password:****
2 在tomcat_home/conf/context.xml文件中的<context></context>之间加入下面的代码：
<Resource
auth="baogenfly"
description="test"
name="jdbc/test"
type="javax.sql.DataSource"
password="test"
driverClassName="com.mysql.jdbc.Driver"
maxWait="5000"
username="test"
url="jdbc:mysql://localhost:3306/test"
maxActive="4"/>
3 在具体的web应用中的WEB-INF目录下的web.xml文件中加入下面的代码：
<resource-ref>
<description> DataSource example</description>
<res-ref-name>jdbc/test</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>baogenfly</res-auth>
</resource-ref>
4 测试代码：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page import="java.util.*" %>
<%@ page import="java.io.*" %>
<%@ page import="java.sql.*" %>
<%@ page import="javax.sql.*" %>
<%@ page import="javax.naming.*" %>
<!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>JNDI TEST</title>
</head>
<body>
<% String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
Context initCtx = new InitialContext();
Context ctx = (Context)initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) ctx.lookup("jdbc/test");
conn = ds.getConnection();
ps = conn.prepareStatement("Select * from balance");
rs = ps.executeQuery();
while(rs.next()){
out.println(rs.getString(1)+"<br>");
out.println(rs.getString(2)+"<br>");
out.println(rs.getString(3)+"<br>");
out.println(rs.getString(4)+"<br>");
}
rs.close();
stmt.close();
%>
</body>
</html>