aspx页面
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
<script language="javascript" type="text/javascript">
function Button1_onclick() {
WebService.getStr(callComplete);
}function aa(){ var List = document.getElementById("dd1"); document.getElementById("Label1").innerHTML = List.options[List.selectedIndex].value;}function callComplete(result) { var List = document.getElementById("dd1"); for (x=List.options.length-1; x > -1; x--) 
{
List.remove(0);
} for(x=0;x<result.length;x++) { var option = document.createElement("option"); option.text = result[x]; option.value = result[x]; if ( window.navigator.appName.toLowerCase().indexOf("microsoft") > -1) List.add(option); else List.add(option, null); } } </script></head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
<Services>
<asp:ServiceReference Path="WebService.asmx" />
</Services>
</asp:ScriptManager>
<input id="Button1" type="button" value="button" language="javascript" onclick="return Button1_onclick()" />
<asp:DropDownList ID="dd1" runat="server">
</asp:DropDownList>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</form>
</body>
</html>
webservice代码：
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Web.Script.Services;
using System.Data;
/// <summary>
/// WebService 的摘要说明
/// </summary>
///
[ScriptService]
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class WebService : System.Web.Services.WebService {
public WebService () {
//如果使用设计的组件，请取消注释以下行
//InitializeComponent();
}
[WebMethod]
public string HelloWorld() {
return "Hello World";
}
[WebMethod]
public string [] getStr()
{
return new string[] {"Hello World","bbb","cccc"};
}