Ajax实现自动刷新页面

所有开发环境：

Eclipse4.2

mySQL5.5

Tomcat6.0(先把数据库驱动程序加到tomcat\\lib下)

建立的数据库中的表dbname=”person” table=”stuscore”

表如下：

前提先建好数据库person 建表代码：

# Host: localhost (Version: 5.5.20)

# Date: 2012-10-16 07:04:12

# Generator: MySQL-Front 5.2 (Build 3.32)

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT

*/;

/*!40101

@OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;

SET

/*!40101

@OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;

SET

/*!40101 SET NAMES utf8 */;

/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE */;

/*!40101 SET

SQL_MODE='STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION' */;

/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES */;

/*!40103 SET SQL_NOTES='ON' */;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS */;

/*!40014 SET UNIQUE_CHECKS=0 */;

/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS */;

/*!40014 SET FOREIGN_KEY_CHECKS=0 */;

#

# Source for table \"stuscore\"

#

DROP TABLE IF EXISTS `stuscore`;

CREATE TABLE `stuscore` (

`Id` int(11) NOT NULL AUTO_INCREMENT,

`name` varchar(255) DEFAULT NULL,

`grade` varchar(255) DEFAULT NULL,

`score` varchar(255) DEFAULT NULL,

`state` int(255) DEFAULT NULL,

PRIMARY KEY (`Id`)

) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

#

# Data for table \"stuscore\"

#

/*!40000 ALTER TABLE `stuscore` DISABLE KEYS */;

INSERT INTO `stuscore` VALUES (1,'杜淳','200401','94.50000',1),(2,'马苏','200401','96.70000',1),(3,'','200402','89.70000',1);

李

晨

','200401','95.40000',1),(4,'

立

方

/*!40000 ALTER TABLE `stuscore` ENABLE KEYS */;

/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;

/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;

/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;

/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;

/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

本次工程结构如下：

其中AutoRefresh.jsp的代码如下：

<%@ page language=\"java\" contentType=\"text/html; charset=utf-8\"

pageEncoding=\"utf-8\"%>

建立servlet程序：

AutoRefreshAction.java代码:

package com.cong;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

//import org.apache.tomcat.dbcp.dbcp.ConnectionFactory;

/**

* Servlet implementation class AutoRefreshAction

*/

public class AutoRefreshAction extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#HttpServlet()

*/

public AutoRefreshAction() {

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

response.setContentType(\"text/xml;charset=utf-8\");

response.setHeader(\"Cache-Control\", \"no-cache\");

PrintWriter out=response.getWriter();

out.println(\"\");

ConnectionFactory factory=new ConnectionFactory();

Connection con=factory.getConnection();

Statement st=null;

ResultSet rs=null;

String strSql=null;

strSql=\"select count(*) from stuscore where state=0 order by id desc\";

try{

st=con.createStatement();

rs=st.executeQuery(strSql);

if(rs.next()){

out.println(\"\"+rs.getString(1)+\"\");

}

}catch(SQLException e){

e.printStackTrace();

}

out.println(\"\");

out.close();

}

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// TODO Auto-generated method stub

}

}

ConnectionFactory.java代码：

package com.cong;

import java.sql.Connection;

import java.sql.DriverManager;

public class ConnectionFactory {

public final static String url=\"jdbc:mysql://localhost:3306/person\";

public final static String user=\"root\";

public final static String password=\"congli\";

Connection getConnection(){

try{

Class.forName(\"com.mysql.jdbc.Driver\");

return (Connection) DriverManager.getConnection(url,user,password);

}

catch(Exception e){

e.printStackTrace();

}

return null;

}

}

Web.xml文件代码：

xmlns:web=\"http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd\" 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\">

ajaxproject

AutoRefresh.jsp

AutoRefreshAction

auto

com.cong.AutoRefreshAction

auto

/auto

运行结果：

然后你在数据库更改state的值变为零，就会看到结果：