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 /**  * XMLHttpRequest Object Pool  *  * @author    legend <>  * @link       * @Copyright  */

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)     sendReq: function (method, url, data, callback)     {         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);                     }                 }             }             catch(e)             {                 alert(e);             }         }     } }; 

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