asp.net DropDownList实现二级联动效果

<tr>  <td>新闻风格：</td>  <td><asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"onselectedindexchanged="DropDownList1_SelectedIndexChanged" ></asp:DropDownList>  </td></tr><tr>  <td>新闻类型：</td>  <td><asp:DropDownList ID="DropDownList2" runat="server">/asp:DropDownList>  </td></tr>

using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;using System.Data.SqlClient;public partial class release_News : System.Web.UI.Page{  protected void DropdownList1()  {    DropDownList1.Items.Add(new ListItem("新闻动态"));    DropDownList1.Items.Add(new ListItem("政务公开"));    DropDownList1.Items.Add(new ListItem("网上办事"));  }  protected void DropdownList2()  {    switch (DropDownList1.SelectedValue)    {      case "新闻动态":        DropDownList2.Items.Clear();        DropDownList2.Items.Add(new ListItem("工作动态"));        DropDownList2.Items.Add(new ListItem("公示公告"));        DropDownList2.Items.Add(new ListItem("经济新闻"));        DropDownList2.Items.Add(new ListItem("省内新闻"));        DropDownList2.Items.Add(new ListItem("热点新闻"));        break;      case "政务公开":        DropDownList2.Items.Clear();        DropDownList2.Items.Add(new ListItem("领导班子"));        DropDownList2.Items.Add(new ListItem("机构设置"));        DropDownList2.Items.Add(new ListItem("计划规划"));        break;      case "网上办事":        DropDownList2.Items.Clear();        DropDownList2.Items.Add(new ListItem("岗位职责"));        DropDownList2.Items.Add(new ListItem("办事流程"));        break;    }  }  protected void Page_Load(object sender, EventArgs e)  {     if (!IsPostBack)    {      DropdownList1();      DropdownList2();    }  }  protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)  {    DropdownList2();  }}

<div>  <asp:DropDownList ID="s1" runat="server"></asp:DropDownList>  <asp:DropDownList ID="s2" runat="server"></asp:DropDownList>  <script language="javascript" type="text/javascript" src="er.js></script>  <script language="javascript" type="text/javascript">setup()</script></div>

function Dsy() { this.Items = {}; } Dsy.prototype.add = function(id,iArray) { this.Items[id] = iArray; } Dsy.prototype.Exists = function(id) { if(typeof(this.Items[id]) == "undefined") return false; return true; }function change(v){ var str="0"; for(i=0;i<v;i++){ str+=("_"+(document.getElementById(s[i]).selectedIndex-1));}; var ss=document.getElementById(s[v]); with(ss){ length = 0; options[0]=new Option(opt0[v],opt0[v]); if(v && document.getElementById(s[v-1]).selectedIndex>0 || !v) { if(dsy.Exists(str)){ ar = dsy.Items[str]; for(i=0;i<ar.length;i++)options[length]=new Option(ar[i],ar[i]); if(v)options[1].selected = true; } } if(++v<s.length){change(v);} } }var dsy = new Dsy();dsy.add("0",["北京市","天津市","河北省","山西省","内蒙古自治区","辽宁省","吉林省","黑龙江省","上海市","江苏省","浙江省","安徽省","福建省","江西省","山东省","河南省","湖北省","湖南省","广东省","广西自治区","海南省","重庆市","四川省","贵州省","云南省","西藏自治区","陕西省","甘肃省","青海省","宁夏回族自治区","新疆维吾尔自治区","香港特别行政区","澳门特别行政区","台湾省","其它"]);dsy.add("0_0",["北京","东城区","西城区","崇文区","宣武区","朝阳区","丰台区","石景山区"," 海淀区（中关村）","门头沟区","房山区","通州区","顺义区","昌平区","大兴区","怀柔区","平谷区","密云县","延庆县","其他"]); dsy.add("0_1",["和平区","河东区","河西区","河北区","南开区","红桥区","塘沽区","汉沽区","大港区","西青区","津南区","武清区","蓟县","宁河县","静海县","其他"]); dsy.add("0_2",["石家庄市","张家口市","承德市","秦皇岛市","唐山市","廊坊市","衡水市","沧州市","邢台市","邯郸市","保定市","其他"]); dsy.add("0_3",["太原市","朔州市","大同市","长治市","晋城市","忻州市","晋中市","临汾市","吕梁市","运城市","其他"]); dsy.add("0_4",["呼和浩特市","包头市","赤峰市","呼伦贝尔市","鄂尔多斯市","乌兰察布市","巴彦淖尔市","兴安盟","阿拉善盟","锡林郭勒盟","其他"]); dsy.add("0_5",["沈阳市","朝阳市","阜新市","铁岭市","抚顺市","丹东市","本溪市","辽阳市","鞍山市","大连市","营口市","盘锦市","锦州市","葫芦岛市","其他"]); dsy.add("0_6",["长春市","白城市","吉林市","四平市","辽源市","通化市","白山市","延边朝鲜族自治州","其他"]); dsy.add("0_7",["哈尔滨市","七台河市","黑河市","大庆市","齐齐哈尔市","伊春市","佳木斯市","双鸭山市","鸡西市","大兴安岭地区(加格达奇)","牡丹江","鹤岗市","绥化市　","其他"]); dsy.add("0_8",["黄浦区","卢湾区","徐汇区","长宁区","静安区","普陀区","闸北区","虹口区","杨浦区","闵行区","宝山区","嘉定区","浦东新区","金山区","松江区","青浦区","南汇区","奉贤区","崇明县","其他"]); dsy.add("0_9",["南京市","徐州市","连云港市","宿迁市","淮安市","盐城市","扬州市","泰州市","南通市","镇江市","常州市","无锡市","苏州市","其他"]);dsy.add("0_10",["杭州市","湖州市","嘉兴市","舟山市","宁波市","绍兴市","衢州市","金华市","台州市","温州市","丽水市","其他"]);dsy.add("0_11",["合肥市","宿州市","淮北市","亳州市","阜阳市","蚌埠市","淮南市","滁州市","马鞍山市","芜湖市","铜陵市","安庆市","黄山市","六安市","巢湖市","池州市","宣城市","其他"]);dsy.add("0_12",["福州市","南平市","莆田市","三明市","泉州市","厦门市","漳州市","龙岩市","宁德市","其他"]);dsy.add("0_13",["南昌市","九江市","景德镇市","鹰潭市","新余市","萍乡市","赣州市","上饶市","抚州市","宜春市","吉安市","其他"]);dsy.add("0_14",["济南市","聊城市","德州市","东营市","淄博市","潍坊市","烟台市","威海市","青岛市","日照市","临沂市","枣庄市","济宁市","泰安市","莱芜市","滨州市","菏泽市","其他"]);dsy.add("0_15",["郑州市","三门峡市","洛阳市","焦作市","新乡市","鹤壁市","安阳市","濮阳市","开封市","商丘市","许昌市","漯河市","平顶山市","南阳市","信阳市","周口市","驻马店市","其他"]);dsy.add("0_16",["武汉市","十堰市","襄樊市","荆门市","孝感市","黄冈市","鄂州市","黄石市","咸宁市","荆州市","宜昌市","随州市","恩施土家族苗族自治州","仙桃市","天门市","潜江市","神农架林区","其他"]);dsy.add("0_17",["长沙市","张家界市","常德市","益阳市","岳阳市","株洲市","湘潭市","衡阳市","郴州市","永州市","邵阳市","怀化市","娄底市","湘西土家族苗族自治州","其他"]);dsy.add("0_18",["广州市","清远市市","韶关市","河源市","梅州市","潮州市","汕头市","揭阳市","汕尾市","惠州市","东莞市","深圳市","珠海市","中山市","江门市","佛山市","肇庆市","云浮市","阳江市","茂名市","湛江市","其他"]);dsy.add("0_19",["南宁市","桂林市","柳州市","梧州市","贵港市","玉林市","钦州市","北海市","防城港市","崇左市","百色市","河池市","来宾市","贺州市","其他"]);dsy.add("0_20",["海口市","三亚市","其他"]);dsy.add("0_21",["渝中区","大渡口区","江北区","沙坪坝区","九龙坡区","南岸区","北碚区","万盛区","双桥区","渝北区","巴南区","万州区","涪陵区","黔江区","长寿区","合川市","永川市","江津市","南川市","綦江县","潼南县","铜梁县","大足县","璧山县","垫江县","武隆县","丰都县","城口县","开县","巫溪县","巫山县","奉节县","云阳县","忠县","石柱土家族自治县","彭水苗族土家族自治县","酉阳土家族苗族自治县","秀山土家族苗族自治县","其他"]);dsy.add("0_22",["成都市","广元市","绵阳市","德阳市","南充市","广安市","遂宁市","内江市","乐山市","自贡市","泸州市","宜宾市","攀枝花市","巴中市","资阳市","眉山市","雅安","阿坝藏族羌族自治州","甘孜藏族自治州","凉山彝族自治州县","其他"]);dsy.add("0_23",["贵阳市","六盘水市","遵义市","安顺市","毕节地区","铜仁地区","黔东南苗族侗族自治州","黔南布依族苗族自治州","黔西南布依族苗族自治州","其他"]);dsy.add("0_24",["昆明市","曲靖市","玉溪市","保山市","昭通市","丽江市","普洱市","临沧市","宁德市","德宏傣族景颇族自治州","怒江傈僳族自治州","楚雄彝族自治州","红河哈尼族彝族自治州","文山壮族苗族自治州","大理白族自治州","迪庆藏族自治州","西双版纳傣族自治州","其他"]);dsy.add("0_25",["拉萨市","那曲地区","昌都地区","林芝地区","山南地区","日喀则地区","阿里地区","其他"]);dsy.add("0_26",["西安市","延安市","铜川市","渭南市","咸阳市","宝鸡市","汉中市","安康市","商洛市","其他"]);dsy.add("0_27",["兰州市 ","嘉峪关市","金昌市","白银市","天水市","武威市","酒泉市","张掖市","庆阳市","平凉市","定西市","陇南市","临夏回族自治州","甘南藏族自治州","其他"]);dsy.add("0_28",["西宁市","海东地区","海北藏族自治州","黄南藏族自治州","玉树藏族自治州","海南藏族自治州","果洛藏族自治州","海西蒙古族藏族自治州","其他"]);dsy.add("0_29",["银川市","石嘴山市","吴忠市","固原市","中卫市","其他"]);dsy.add("0_30",["乌鲁木齐市","克拉玛依市","喀什地区","阿克苏地区","和田地区","吐鲁番地区","哈密地区","塔城地区","阿勒泰地区","克孜勒苏柯尔克孜自治州","博尔塔拉蒙古自治州","昌吉回族自治州 伊犁哈萨克自治州","巴音郭楞蒙古自治州","河子市","阿拉尔市","五家渠市","图木舒克市","其他"]);dsy.add("0_31",["香港","其他"]);dsy.add("0_31",["澳门","其他"])dsy.add("0_32",["台湾","其他"])var s=["s1","s2"]; var opt0 = ["请选择","请选择"]; function setup() { for(i=0;i<s.length-1;i++) document.getElementById(s[i]).onchange=new Function("change("+(i+1)+")"); change(0); }