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];
            }
        }

        this._objPool[this._objPool.length] = this._createObj();

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

    _createObj: function ()
    {
       	if(window.XMLHttpRequest){ 
			objXMLHttp = new XMLHttpRequest();
			if (objXMLHttp.overrideMimeType) {
				objXMLHttp.overrideMimeType("text/xml");
			}
		}
		else if (window.ActiveXObject){ 
			try {
				objXMLHttp = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
			try {
				objXMLHttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
			}
		}
		if (!objXMLHttp) { 
			window.alert("can't create XMLHttpRequest object.");
			return null;
		}          
        
        if (objXMLHttp.readyState == null)
        {
            objXMLHttp.readyState = 0;

            objXMLHttp.addEventListener("load", function ()
                {
                    objXMLHttp.readyState = 4;
                    
                    if (typeof objXMLHttp.onreadystatechange == "function")
                    {
                        objXMLHttp.onreadystatechange();
                    }
                },  false);
        }

        return objXMLHttp;
    },
    

    sendReq: function (method, url, data, callback,container)
    {
        var objXMLHttp = this._getInstance();

        with(objXMLHttp)
        {
            try{
                if (url.indexOf("?") > 0){
                    url += "&randnum=" + Math.random();
                }
                else{
                    url += "?randnum=" + Math.random();
                }
                open(method, url, true);
                setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=gb2312');
				setRequestHeader("If-Modified-Since","0");
				//setRequestHeader("Content-Type","text/html");
				//setRequestHeader("Content-Type","gb2312");
                send(data);
                onreadystatechange = function (){                   
                    if (objXMLHttp.readyState == 4 && (objXMLHttp.status == 200 || objXMLHttp.status == 304))
                    {
                        callback(objXMLHttp,container);						
						//alert(objXMLHttp.readyState);
						//alert(objXMLHttp.status);
						//alert(objXMLHttp.responseText);
                    }
                }
            }
            catch(e){
                alert(e);
            }
        }
    }
};
function $() {
  var elements = new Array();

  for (var i = 0; i < arguments.length; i++) {
    var element = arguments[i];
    if (typeof element == 'string')
      element = document.getElementById(element);

    if (arguments.length == 1)
      return element;

    elements.push(element);
  }

  return elements;
}

//function $(o){return document.getElementById(o);}