作者：legend
出处：http://>
*@linkhttp://www.ugia.cn/?p=85
*@Copyrightwww.ugia.cn
*/

varXMLHttp={
_objPool:[],

_getInstance:function()
{
for(vari=0;i<this._objPool.length;i++)
{
if(this._objPool[i].readyState==0||this._objPool[i].readyState==4)
{
returnthis._objPool[i];
}
}

//IE5中不支持push方法
this._objPool[this._objPool.length]=this._createObj();

returnthis._objPool[this._objPool.length-1];
},

_createObj:function()
{
if(window.XMLHttpRequest)
{
varobjXMLHttp=newXMLHttpRequest();

}
else
{
varMSXML=['MSXML2.XMLHTTP.5.0','MSXML2.XMLHTTP.4.0','MSXML2.XMLHTTP.3.0','MSXML2.XMLHTTP','Microsoft.XMLHTTP'];
for(varn=0;n<MSXML.length;n++)
{
try
{
varobjXMLHttp=newActiveXObject(MSXML[n]);
break;
}
catch(e)
{
}
}
}

//mozilla某些版本没有readyState属性
if(objXMLHttp.readyState==null)
{
objXMLHttp.readyState=0;

objXMLHttp.addEventListener("load",function()
{
objXMLHttp.readyState=4;

if(typeofobjXMLHttp.onreadystatechange=="function")
{
objXMLHttp.onreadystatechange();
}
},false);
}

returnobjXMLHttp;
},

//发送请求(方法[post,get],地址,数据,回调函数)
sendReq:function(method,url,data,callback)
{
varobjXMLHttp=this._getInstance();

with(objXMLHttp)
{
try
{
//加随机数防止缓存
if(url.indexOf("?")>0)
{
url+="&randnum="+Math.random();
}
else
{
url+="?randnum="+Math.random();
}

open(method,url,true);

//设定请求编码方式
setRequestHeader('Content-Type','application/x-www-form-urlencoded;charset=UTF-8');
send(data);
onreadystatechange=function()
{
if(objXMLHttp.readyState==4&&(objXMLHttp.status==200||objXMLHttp.status==304))
{
callback(objXMLHttp);
}
}
}
catch(e)
{
alert(e);
}
}
}
};


示例：
复制代码 代码如下:
<scripttype="text/javascript"src="xmlhttp.js"></script>
<scripttype="text/javascript">
functiontest(obj)
{
alert(obj.statusText);
}

XMLHttp.sendReq('GET','http://www.ugia.cn/wp-data/test.htm','',test);
XMLHttp.sendReq('GET','http://www.ugia.cn/wp-data/test.htm','',test);
XMLHttp.sendReq('GET','http://www.ugia.cn/wp-data/test.htm','',test);
XMLHttp.sendReq('GET','http://www.ugia.cn/wp-data/test.htm','',test);

alert('Poollength:'+XMLHttp._objPool.length);
</script>