function Cook_city(str,classid,nextid,smallid) {
	var MenuIdArr, MenuFieldArr, MenuClass;
	MenuIdArr = new Array();
	MenuFieldArr = new Array();
	MenuClass = 3;
	MenuIdArr[1] = "CityID_1";
	MenuIdArr[2] = "CityID_2";
	MenuIdArr[3] = "CityID_3";
	MenuFieldArr[1] = "f_title";
	MenuFieldArr[2] = "f_title";
	MenuFieldArr[3] = "f_title";
	if (window.XMLHttpRequest) {
		// Mozilla, Safari, ...
		http_request = new XMLHttpRequest();
	} else if (window.ActiveXObject) {
		// IE
		http_request = new ActiveXObject("Microsoft.XMLHTTP");
	}
	if (smallid==null){
		var linkurl = "ajax.asp?classid="+classid+"&sel="+str+"&fieldname="+MenuFieldArr[classid+1];
	}else{
		var linkurl = "ajax.asp?smallid=1&classid="+classid+"&sel="+str+"&fieldname="+MenuFieldArr[classid+1];
	}
	//alert(linkurl);
	http_request.open("GET", linkurl, false);
	http_request.send(null);
	//服务器端处理返回的是经过escape编码的字符串.
	//在页面显示服务器查询结果
	var returntxt = unescape(http_request.responseText);
	//alert(returntxt);
	//通过XMLHTTP返回数据,开始构建Select.
	//BuildSel(returntxt,eval("document.all."+MenuIdArr[classid+1]))
	BuildSel_cook(returntxt, document.getElementById(MenuIdArr[classid+1]),nextid);
	//============更改下下级以下菜单为空==============
	
	var kkk;
	for (kkk=classid+2; kkk<=MenuClass; kkk++) {
		submenu = document.getElementById(MenuIdArr[kkk]);
		submenu.length = 1;
		submenu.options[0].selected = true;
	}
}
function BuildSel_cook(str, sel,nextid) {
	//alert(id);
	//alert(str);
	//alert(sel);
	/*
	//*--------------- BuildSel(str,sel) -----------------
	//* BuildSel(str,sel) 
	//* 功能:通过str构建Select.
	//* 参数:str,字符串,由服务端返回的.有特定结构"字符串1|,字符串2,字符串3"
	//*          也可为"字符串1序号|字符串1文本,字符串2序号|字符串2文本,字符串3序号|字符串3文本",如本例
	//* 参数:sel,要构建的Select
	//* 实例:BuildSel(unescape(oBao.responseText),document.all.class_id1)
	//*--------------- BuildSel(str,sel) -----------------
	*/
	//先清空原来的数据.
	sel.options.length = 0;
	var arrstr = new Array();
	arrstr = str.split(",");
	//开始构建新的Select.
	sel.options.add(new Option("请选择", ""));
	if (str.length>0) {
		for (var i = 0; i<arrstr.length; i++) {
			t=i+1
			//分割字符串
			var subarrstr = new Array();
			subarrstr = arrstr[i].split("|");
			//生成下级菜单
			sel.options.add(new Option(subarrstr[1], subarrstr[0]));
			
			//alert(subarrstr[0]+"|"+nextid+"|"+sel.options[t].name);
			//alert(id);
			if (subarrstr[0]==nextid){
				sel.options[t].selected = true;
				var choosetype=true;
			}
			
		}
		if (choosetype!=true){
			sel.options[0].selected = true;
		}
	}
}