利用ajax updatepanel和DropdownList实现省市无刷新联动

Web.config 设置：

 <system.web>   下加入：

<httpHandlers>
        <remove verb="*" path="*.asmx"/>
        <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>
</httpHandlers>

<httpModules>
        <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
</httpModules>

<compilation debug="true" strict="false" explicit="true">
   <assemblies>
    <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
      </assemblies>
</compilation>

 <pages validateRequest="false">   下加入：

<controls>
            <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            <add tagPrefix="webdiyer" namespace="Wuqi.Webdiyer" assembly="AspNetPager"/>
            <!--**********使用了AspNetPager7.0 ，故加此句为了方便后面的页面不用再加**************-->
</controls>

*******************Web.config 设置完毕*************************

页面前台：

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate> 

         //这里放dropdownlist控件
       </ContentTemplate>
 </asp:UpdatePanel>

后台代码：

  按照平常一样绑定数据就OK！