function CreateAJAX() {
    var ajax;
    if (window.ActiveXObject) {
        var list = ["MSXML2.XMLHttp.6.0", "MSXML2.XMLHttp.5.0", "MSXML2.XMLHttp.4.0", "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp", "Microsoft.XMLHttp"];
        for (var i = 0; i < list.length; i++) {
            try {
                ajax = new ActiveXObject(list[i]);
                return ajax;
            }
            catch (ie) {
                //IE浏览器
            }
        }
    }
    else {
        try {
            ajax = new XMLHttpRequest();
            return ajax;
        }
        catch (other) {
            //其他浏览器
        }
    }
}

var UdowsAjax = function (udows) {
    // 初始化
    var type = udows.type;                  //type参数,可选      
    var url = udows.url;                    //url参数，必填      
    var data = udows.data;                  //data参数可选，只有在post请求时需要        
    var dataType = udows.dataType;          //datatype参数可选      
    var success = udows.success;            //回调函数可选
    var beforeSend = udows.beforeSend;      //回调函数可选
    var complete = udows.complete;          //回调函数可选
    var error = udows.error;                //回调函数可选
    if (type == null) {                     //type参数可选，默认为get
        type = "get";
    }
    if (dataType == null) {                 //dataType参数可选，默认为text
        dataType = "text";
    }
    var ajax = CreateAJAX();                // 创建ajax引擎对象
    ajax.open(type, url, true);             // 打开
    // 发送
    if (type.toLowerCase() == "get") {
        ajax.send(null);
    }
    if (type.toLowerCase() == "post") {
        ajax.setRequestHeader("content-type", "application/x-www-form-urlencoded");
        ajax.send(data);
    }
    ajax.onreadystatechange = function () {
        if (ajax.readyState == 4 && ajax.status == 200) {
            if (dataType.toLowerCase() == "text") {
                if (success != null) {
                    success(ajax.responseText);
                }
            } else if (dataType.toLowerCase() == "xml") {
                if (success != null) {
                    success(ajax.responseXML);
                }
            } else if (dataType.toLowerCase() == "json") {
                if (success != null) {
                    success(eval("(" + ajax.responseText + ")"));
                }
            }
        }
    };
};