servlet 如何渠道jquery ajax 中Select的值

function f() { new Ajax.Request("servlet/GetProvinceServlet", { method : "post", onSuccess : function(req) { var provinces = req.responseText.evalJSON(); for (i = 0; i < provinces.length; i++) { var province = provinces[i]; var op1 = new Option(province.name, i); $('s1').options[i] = op1; } f1(); } }); } function getXmlHttpRequest() { var xmlHttpRequest = null; if ((typeof XMLHttpRequest) != 'undefined') { xmlHttpRequest = new XMLHttpRequest(); } else { xmlHttpRequest = new ActiveXObject('Microsoft.XMLHttp'); } return xmlHttpRequest; } function f1() { var xmlReq = getXmlHttpRequest(); var url = "servlet/GetCityServlet"; xmlReq.open("post", url, true); xmlReq.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xmlReq.onreadystatechange = function() {//匿名函数 if (xmlReq.readyState == 4) {//服务器响应已经完成 //alert(xmlReq.status); if (xmlReq.status == 200) {//如果服务器返回的是错误信息 var citys = xmlReq.responseText.evalJSON();//获得数据 $('s2').innerHTML = '';//清空第二个下拉列表中的类容 for (i = 0; i < citys.length; i++) { var city = citys[i]; var op1 = new Option(city.name, i); $('s2').options[i] = op1; } } else { alert("error"); } } }; xmlReq.send("prvince=" + $("s1").value); }