function ajaxRequest(url,data,method,fn) {
            var request = new XMLHttpRequest();
            request.open(method,url,true);
            request.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=utf-8");
            request.onreadystatechange = function () {
                if (request.readyState == 4 && request.status == 200)
                    fn(eval('(' + request.responseText + ')'));
                else if (request.readyState == 4 && request.status == 500) {
                    console.log(request.responseText);
                    alert("未知错误");
                    return false;
                }
            }
            var params = "";
            if (typeof data == 'object') {
                for (var d in data)
                    params += d + "=" + data[d] + "&";
                params = params.substr(0,params.length - 1);
            }
            else
                params = data;
            request.send(params);
        }