var xmlHttp;
var XMLHTTP = {
    _objPool: [],
    _getInstance: function ()
    {
        //for (var i = 0; i < this._objPool.length; i ++)
//        {
//            if (this._objPool[i].readyState == 0 || this._objPool[i].readyState == 4)
//            {
//                return this._objPool[i];
//            }
//        }

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

        return this._objPool[this._objPool.length - 1];
    },
    _createObj: function ()
    {
        if (window.XMLHttpRequest)
        {
            var objXMLHttp = new XMLHttpRequest();

        }
        else
        {
            var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
            for(var n = 0; n < MSXML.length; n ++)
            {
                try
                {
                    var objXMLHttp = new ActiveXObject(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 (typeof objXMLHttp.onreadystatechange == "function")
                    {
                        objXMLHttp.onreadystatechange();
                    }
                },  false);
        }

        return objXMLHttp;
    },
    // 发送请求(方法[post,get], 地址, 数据, 回调函数,是否异步)//XMLHTTP.sendReq('GET',url,'','views','...');    
    sendReq: function (method, url, data, obj,hint)
    {
		if (hint =="" || typeof(hint) == "undefined")
		{
			hint = "数据加载中...";
		}
		
        var objXMLHttp = 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);
						document.getElementById(obj).innerHTML = objXMLHttp.responseText;
                    }
					else
					{
						document.getElementById(obj).innerHTML = "<div style='color:#cccccc;font-weight:100;font-size:12px;text-align:center;'>"+hint+"</div>";
					}
                }
            }
            catch(e)
            {
                alert(e);
            }
        }
    }
}
function GetXmlHttpObject()
{
	var xmlHttp=null;
	try
	{
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
	}
	catch (e)
	{
	// Internet Explorer
		try
		{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e)
		{
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}