http://www.java3z.com/cwbwebhome/article/article8/81381.html?id=3866
1.实现思路
在ajax回调函数中用方法setTimeout("load()", 1000)，这样就会每隔1秒自动去请求新的信息，实现自动刷新的功能。
2.实例
(1)index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>ajax+servlet实现自动刷新页面</title>
<mce:script type="text/javascript"><!--
function $(id){
return document.getElementById(id);
}
var xmlHttp;
//根据浏览器创建xmlHttpRequest对象
function getXmlHttpRequest() {
//针对FireFox,Mozillar,Opera,Safari,IE7,IE8
if(window.XMLHttpRequest)
return new XMLHttpRequest();
//针对IE5，IE5.5，IE6
else if (window.ActiveXObject){
//两个可以用于创建XMLHTTPRequest对象的控件名称,保存在一个JS数组中。
var activexName = ["MSXML2.XMLHTTP","Microsoft.XMLHTTP"];
for(var i = 0; i<activexName.length; i++){
//取出一个控件名进行创建，如果成功就终止循环
try{
return new ActiveXObject(activexName[i]);
break;
}catch(e){
return null;
}
}
}
}
function load(){
xmlHttp=getXmlHttpRequest();
var url="servlet/GetMp3Info";
// 注册回调函数,只写函数名，不能写括号，写括号表示调用函数
xmlHttp.onreadystatechange = getResult;
// 确定发送请求的方式和URL以及是否同步执行下段代码
xmlHttp.open("GET", url, true);
//发送数据，开始和服务器进行交互
xmlHttp.send(null);
}
//回调函数
function getResult(){
if (xmlHttp.readyState == 4) { // 判断对象状态
if (xmlHttp.status == 200) { // 信息已经成功返回，开始处理信息
var text=xmlHttp.responseXML;
var name=text.getElementsByTagName("name")[0].firstChild.nodeValue;
var number=text.getElementsByTagName("number")[0].firstChild.nodeValue;
$("name").innerHTML=name;
$("number").innerHTML=number;
setTimeout("load()", 1000);
} else {
alert("请求的出错啦!");
}
}
}
// --></mce:script>
</head>
<body onload="load()">
<form>
<table>
<thead>
<tr>
<th colspan="2">
</th>
</tr>
</thead>
<tbody>
<tr>
<td>名称</td>
<td id="name"></td>
</tr>
<tr>
<td>数量</td>
<td id="number"></td>
</tr>
</tbody>
</table>
</form>
</body>
</html>
(2)GetMp3Info.java(servlet)
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GetMp3Info extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/xml;charset=utf-8");
response.setCharacterEncoding("utf-8");
response.setHeader("Cache-Control","no-cache");
String name[]={"索尼","清华紫光","纽曼","步步高"};
String str="";
str+="<mp3>";
str+="<name>"+name[new Random().nextInt(name.length)]+"</name>";
str+="<number>"+new Random().nextInt(1000)+"</number>";
str+="</mp3>";
System.out.println("str="+str);
response.getWriter().write(str);
response.getWriter().flush();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
}
(3)web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>GetMp3Info</servlet-name>
<servlet-class>GetMp3Info</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>GetMp3Info</servlet-name>
<url-pattern>/servlet/GetMp3Info</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
3.运行效果
