<?xml version="1.0" encoding="utf-8"?>
<Context>
    Resource
    name="mySource"
    type="javax.sql.DataSource"
    username="root"
    password
    driverClassName="com.MysqL.jdbc.Driver"
    url="jdbc:MysqL:///java"
    maxActive="8"
    maxIdle="4"
    />
</>

package com.tsh.web;

import java.io.IOException;
 java.sql.Connection;
 java.sql.ResultSet;
 java.sql.Statement;

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




/**
 */
public class DataSourceTest extends HttpServlet {
       
    /**
     */
    public DataSourceTest() {
        super();
        // TODO Auto-generated constructor stub
    }

    protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
         TODO Auto-generated method stub
void doPost(HttpServletRequest request,IOException {
    }
    /**
     * 创建后就会启动
     */
    @Override
    void init()  ServletException {
        try {
            注意导包javax.naming.Context;
            Context context= new InitialContext();
            Context jndi=(Context) context.lookup("java:comp/env");
            DataSource source =(DataSource) jndi.lookup("mySource");
            注意导包 java.sql.Connection;
            Connection conn=source.getConnection();
            获取传输器对象
            Statement statement=conn.createStatement();
            获取结果集对象
            ResultSet resultSet=statement.executeQuery("select * from user"遍历
            while(resultSet.next()){
                String username=resultSet.getString("username");
                System.out.println(username);
            }
            关闭资源
            resultSet.close();
            statement.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

    servlet>
        servlet-name>DataSourceTestservlet-class>com.tsh.web.DataSourceTestload-on-startup>1servlet-mappingurl-pattern>/Servlet/DataSourceTest>

    >