关于ajax post数据的问题

[yoyibf]

<script language='JavaScript'>
<!--
/*ajaxز*/
//ȫֱ
var msxml = new Array("Msxml2","Msxml3","Microsoft");
var req;
function yyajax(uri,method,asy,value)
{
//Ա;
this.uri = uri;
this.method = method;
this.asy = method;
this.value = value;
this.debug = false; //


this.serverConnect = function()
{
if(window.ActiveXObject)//ie;
{
var ieversion =parseFloat(navigator.appVersion);

try{
if(ieversion<5)
{
for(var i=0;i<msxml.length;i++){
try{
req = new ActiveXObject(msxml[i]+".XMLHTTP");

}catch(e){}
}

}else
throw("error!");
}catch(error)
{
alert(error);
return false;
}
}else if(window.XMLHttpRequest)//
{
try{
req = new XMLHttpRequest();

if(req.overrideMimeType)
req.overrideMimeType("text/xml");

}catch(E){return false;}//;
}


//
if(!req)
return false;
req.onreadystatechange = this.processRequest;

this.send();
}

this.send = function(){

if(this.method.toLowerCase()=="post")
{
//req.setRequestHeader("Method", "POST " + this.uri + " HTTP/1.1");
//req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=utf-8');
alert(this.value);
req.open(this.method,this.uri,this.method,this.asy);
req.send(this.value);
}
else{
req.open(this.method,this.uri,this.method,this.asy);
req.send("");
}
}

this.processRequest = function(){
if(req.readyState==4)
{ document.getElementById("rel").innerHTML="";
if(req.status==200)
alert(req.responseText);
else
alert("error!");
}else
document.getElementById("rel").innerHTML="正在加载....";
}
//postxml;
//utf-8;

this.printXmlValue = function(){
var str="<?xml version='1.0' encoding='utf-8'?>\n";
str+="<yyajax>\n";

if(this.value=="object")
{
for(var i=0;i<this.value.length;i++)
str+= "<data_"+i+">"+this.value[i]+"</data_"+i+">\n";
}else
str+= "<data>"+this.value+"</data>\n";

str+="</yyajax>\n";

return str;
}
}//yyajax class:


var obj = new yyajax("http://localhost/test.php","POST","true",'username=asdfasdf');
obj.serverConnect();

//-->
</script>
<div id='rel'></div>

=========
test.php
<?php
echo "username".$_REQUEST['username'];

?>
在ajax post方式传送数据给test.php页面的时候，我如何获得该数据变量？
还有，当我在post方式的时候执行
req.setRequestHeader("Method", "POST " + this.uri + " HTTP/1.1");
req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=utf-8');
任何一句，程序将没有任何结果和提示
＝＝＝＝＝＝＝＝＝
想知道ajax使用post方式传数据是什么样的过程？
我本来还想是否是生成xml文档，上面也有这样一个函数，不过结果还是不行
等待帮忙！

[Wadelau]

ajax的post和get跟普通的表单没有区别啊，

http://www.wadelau.net/gtajax/index.html