终于找到一个ASP.NET实现进度条的例子.
建立一个WEB工程，添加新项->HTML页面，命名为ProgressBar.htm，内容如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" id="mainWindow">
<head>
<title>无标题页</title>
<script language="javascript">
function SetPorgressBar(pos)
{
//设置进度条居中
var screenHeight = window["mainWindow"].offsetHeight;
var screenWidth = window["mainWindow"].offsetWidth;
ProgressBarSide.style.width = Math.round(screenWidth / 2);
ProgressBarSide.style.left = Math.round(screenWidth / 4);
ProgressBarSide.style.top = Math.round(screenHeight / 2);
ProgressBarSide.style.height = "21px";
ProgressBarSide.style.display = "";
//设置进度条百分比
ProgressBar.style.width = pos + "%";
ProgressText.innerHTML = pos + "%";
}
//完成后隐藏进度条
function SetCompleted()
{
ProgressBarSide.style.display = "none";
}
</script>
</head>
<body>
<div id="ProgressBarSide" style="position:absolute;height:21x;width:100px;color:Silver;border-width:1px;border-style:Solid;display:none">
<div id="ProgressBar" style="position:absolute;height:21px;width:0%;background-color:#3366FF"></div>
<div id="ProgressText" style="position:absolute;height:21px;width:100%;text-align:center"></div>
</div>
</body>
</html>