ajax XMLHttpRequest 对象建立

/** * XMLHttpRequest Object Pool * * @author legend <legendsky@hotmail.com> * @link http://www.ugia.cn/?p=85 * @Copyright www.ugia.cn */

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); } } } };