struts2--数据源应用

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1、在WebRoot/MWTA-INF下创建一个名为context.xml的配置文件，文件内容如下。

<?xml version="1.0" encoding="UTF-8"?><Context path = "/dbtom" docBase = "dbtom" reloadable = "true" crossContext = "true">  <Resource   name = "jdbc/dbtom"   type = "javax.sql.DataSource"   username = "root"   password = "root"   driverClassName = "com.mysql.jdbc.Driver"   url = "jdbc:mysql://localhost:3306/user"  /></Context>

在<Resource>元素中，以上几个属性均为必填属性。

2、创建java类（DbPool.java）

package com.conDB;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import javax.naming.Context;import javax.naming.InitialContext;import javax.sql.DataSource;public class DbPool {  private Connection connection;  public void getConn() {  try {Context initcContext = new InitialContext(); //初始化context对象Context envContext = (Context) initcContext.lookup("java:comp/env");DataSource dSource = (DataSource) envContext.lookup("jdbc/dbtom"); //获取数据源connection = dSource.getConnection();System.out.println("获取连接成功");} catch (Exception e) {System.out.println("获取连接失败");}}    public ResultSet query(String sql) {ResultSet rs = null;if(connection == null){getConn();//如果为空，则获取连接}PreparedStatement ps;try {ps = connection.prepareStatement(sql);rs = ps.executeQuery();} catch (Exception e) {System.out.println("query is failed!");}    return rs;}}

3、在jsp页面查询数据库中的信息：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%@ taglib prefix = "s" uri = "/struts-tags" %><%@ page import="java.sql.*"%><%@ page import="com.conDB.*" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>  </head>    <body>    <%      DbPool pool = new DbPool();  //初始化实例对象      String sql = "select * from info";      ResultSet rs = pool.query(sql);      if(rs != null)      while(rs.next()){      out.print("姓名："+rs.getString(1));      out.print("         密码："+rs.getString(2));      out.print("<br>");      }      else System.out.println("rs is null");     %>  </body></html>

根据数据库中的信息，查询结果如下：

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