让ajax更加友好的实现方法(实时显示后台处理进度。)

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// 下面设置Content-Type:application/x-javascript 是为了适应Webkit的浏览器(chrome,safari)
response.setHeader("Content-Type","application/x-javascript");
int count = 6; // 处理6条数据
for(int i=0;icount;i++){
// 处理完毕一条，输出结果到客户端
out.println(i+1);
out.flush();
// 这里假设每条数据处理时间为1秒
Thread.currentThread().sleep(1000);
}
%>

!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">
head>
style>
#divProgress{width:300px;height:24px;position:relative;}
#divProgress div{position:absolute;left:0;top:0;height:24px;}
#progressBg{background-color:#B9F8F9;z-index:10;}
#progressText{z-index:15;text-align:center;width:100%;}
/style>
/head>
body>
div id="divProgress">
div id="progressBg">/div>
div id="progressText">/div>
/div>
br />
button onclick="send()">提交数据/button>
script>
var t = document.getElementById("progressText");
var bg = document.getElementById("progressBg");
function send(){
t.innerHTML = "loading...";
bg.style.width = "0px";
var xhr = new window.XMLHttpRequest();
if(!window.XMLHttpRequest){
try {
xhr = new window.ActiveXObject("Microsoft.XMLHTTP");
} catch(e) {}
}
xhr.open("post","http://localhost:801/ChunkTest/chunk.jsp?count=6");
var oldSize=0;
xhr.onreadystatechange = function(){
if(xhr.readyState > 2){
var tmpText = xhr.responseText.substring(oldSize);
oldSize = xhr.responseText.length;
if(tmpText.length > 0 ){
// 设置文本
t.innerHTML = tmpText + "/6";
// 设置进度条
var width = parseInt(tmpText)/6*300;
bg.style.width = width+"px";
}
}
if(xhr.readyState == 4){
// 请求执行完毕
t.innerHTML = "执行完毕";
bg.style.width = "300px";
}
}
xhr.send(null);
}
/script>
/body>
/html>