Tomcat布置数据源，mysql例子

项目中的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>DataSourceTest</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description>testing DataSource in Tomcat with mysql</description>
    <display-name>DataSourceTest</display-name>
    <servlet-name>DataSourceTest</servlet-name>
    <servlet-class>com.gdret.intern.servlet.DataSourceTest</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>DataSourceTest</servlet-name>
    <url-pattern>/DataSourceTest</url-pattern>
  </servlet-mapping>
</web-app>

项目下的context.xml

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/DataSourceTest" 	docBase="DataSourceTest" debug="0">
	<Resource name="jdbc/mysql" auth="Container" type="javax.sql.DataSource"
	maxActive="20"
	maxIdle="2"
	maxWait="3000"
	url="jdbc:mysql://localhost:3306/test"
	driverClassName="com.mysql.jdbc.Driver"
	username="root"
	password="" />
	
</Context>

测试用servlet

package com.gdret.intern.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import javax.naming.*;
import javax.sql.*;

import java.sql.*;
/**
 * Servlet implementation class DataSourceTest
 */
public class DataSourceTest extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DataSourceTest() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		Context ctx;
		try {
			ctx = new InitialContext();
			DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
			Connection conn = ds.getConnection();
			PreparedStatement ps = conn.prepareStatement("select * from user");
			ResultSet rs = ps.executeQuery();
			response.setContentType("text/html");
			PrintWriter out = response.getWriter();
	        
			while(rs.next()){
				System.out.println(rs.getInt("id")+" "+
						rs.getString("username")+ " " + 
						rs.getString("password")+ " " + 
						rs.getString("email"));
				out.println(rs.getInt("id")+" "+
						rs.getString("username")+ " " + 
						rs.getString("password")+ " " + 
						rs.getString("email"));
			}
			conn.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}

主要参考：

http://blog.youkuaiyun.com/xiazdong/article/details/6898774

http://blog.youkuaiyun.com/xiazdong/article/details/6904506

http://blog.youkuaiyun.com/cyxlzzs/article/details/7352837

http://blog.sina.com.cn/s/blog_4be5d1c10100wx4q.html

http://blog.sina.com.cn/s/blog_4be5d1c10100wx4v.html

http://annegu.iteye.com/blog/409176