业务逻辑：在web应用建立进度条。
页面：progressBar.jsp
<%@ page contentType="text/html; charset=GBK" %>
<html>
<head>
<title>
Ajax进度条
</title>
<script type="text/javascript">
//xmlHttpRequest对象
var xmlHttp;
var key;
//进度条颜色
var bar_color='gray';
var span_id='block';
var clear=" "
//创建xmlHttpRequest对象
function createXMLHttpRequest(){
if (window.ActiveXObject){
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
}
//执行方法
function go(){
createXMLHttpRequest();
checkDiv();
var url = "ProgressBarServlet?task=create";
//隐藏按钮
var button = document.getElementById("go");
button.disabled = true;
xmlHttp.open("GET",url,true);
xmlHttp.onreadystatechange = goCallback;
xmlHttp.send(null);
}
//回调方法
function goCallback(){
if (xmlHttp.readyState == 4){
if (xmlHttp.status == 200){
//设置更新时间
setTimeout("pollServer()",2000);
}
}
}
//刷新，重新发送
function pollServer(){
createXMLHttpRequest();
var url = "ProgressBarServlet?task=poll&key=" + key;
xmlHttp.open("GET",url,true);
xmlHttp.onreadystatechange = pollCallback;
xmlHttp.send(null);
}
//回调方法
function pollCallback(){
if (xmlHttp.readyState == 4){
if (xmlHttp.status == 200){
//完成百分比
var percent_complete = xmlHttp.responseXML.getElementsByTagName("percent")[0].firstChild.data;
var index = processResult(percent_complete);
var (var i = 1; i <= index;i++){
var elem = document.getElementById("block" + i);
elem.innerHTML = clear;
elem.style.backgroundColor = bar_color;
var next_cell = i + 1;
if (next_cell > index && next_cell < = 9){
document.getElementById("block" + next_cell).innerHTML = percent_complete + "%";
}
}
if (index < 9){
setTimeout("pollServer()",2000);
}else{
document.getElementById("complete").innerHTML = "Complete!";
document.getElementById("go").disabled = false;
}
}
}
}
//解析结果
function processResult(){
var ind;
if (percent_complete.length == 1){
ind = 1;
}else if (percent_complete.length == 2){
ind = percent_complete.substring(0,1);
}else(
ind = 9;
}
return ind;
}
//检查提示层信息
function checkDiv(){
var progress_bar = document.getElementById("progressBar");
if (progress_bar.style.visibility == "visible"){
//清除进度条
clearBar();
document.getElementById("complete").innerHTML = "";
}else{
progress_bar.style.visibility = "visible";
}
}
//清除进度条
function clearBar(){
for (var i = 1; i < 10; i++){
var elem = document.getElementById("block" + i);
elem.innerHTML = clear;
elem.style.backgroundColor = "white";
}
}
</script>
</head>
<body bgcolor="#ffffff">
<h1>
Ajax进度条示例
</h1>
运行进度条:
<input type="button" value="运行" id="go" onclick="go()"/>
<p>
</p>
<table align="center">
<tbody>
<tr>
<td><div id="progressBar" style="padding:2px;border:solid black 2px;visibility?hidden">
<span id="block1"> </span>
<span id="block2"> </span>
<span id="block3"> </span>
<span id="block4"> </span>
<span id="block5"> </span>
<span id="block6"> </span>
<span id="block7"> </span>
<span id="block8"> </span>
<span id="block9"> </span>
</div></td>
</tr>
<tr><td align="center" id="complete"></td> </tr>
</tbody>
</table>
</body>
</html>
服务器端：ProgressBarServlet.java
package ajaxvalidation;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class ProgressBarServlet
extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=GBK";
//计数器
private int counter = 1;
//Initialize global variables
public void init() throws ServletException {
}
//处理get方法
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
//得到任务类型
String task = request.getParameter("task");
//返回的xml字符串
String res = "";
//第一次，创建进度条
if (task.equals("create")){
res = "<key>1</key>";
counter = 1;
}else{
//完成百分比
String percent = "";
switch(counter){
case 1:percent = "10";break;
case 2:percent = "23";break;
case 3:percent = "35";break;
case 4:percent = "51";break;
case 5:percent = "64";break;
case 6:percent = "73";break;
case 7:percent = "89";break;
case 8:percent = "100";break;
}
counter++;
res = "<percent>" + percent + "</percent>";
}
PrintWriter out = response.getWriter();
response.setContentType("text/xml");
response.setHeader("Cache-Control","no-cache");
out.println("<response>");
out.println(res);
out.println("</response>");
out.close();
}
//Clean up resources
public void destroy() {
}
}
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/jawsy/archive/2006/07/18/936457.aspx