可以不可以在 2.cs代码 using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Drawing; using System.Web; using System.Web.SessionState; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.HtmlControls; namespace AjaxTest { /**////

/// Summary description for WebForm1. ///

public class WebForm1 : System.Web.UI.Page { protected System.Web.UI.WebControls.DropDownList DropDownList1; protected System.Web.UI.WebControls.DropDownList DropDownList2; protected System.Web.UI.WebControls.TextBox TextBox1; protected System.Web.UI.WebControls.DropDownList DropDownList3; private void Page_Load(object sender, System.EventArgs e) { Ajax.Utility.RegisterTypeForAjax(typeof(AjaxMethod)); if(!Page.IsPostBack) { this.DropDownList1.DataSource=AjaxMethod.GetProvinceList(); this.DropDownList1.DataTextField="province"; this.DropDownList1.DataValueField="provinceID"; this.DropDownList1.DataBind(); this.DropDownList1.Attributes.Add("onclick","cityResult();"); this.DropDownList2.Attributes.Add("onclick","areaResult();"); } } Web Form Designer generated code#region Web Form Designer generated code override protected void OnInit(EventArgs e) { // // CODEGEN: This call is required by the ASP.NET Web Form Designer. // InitializeComponent(); base.OnInit(e); } /**////

/// Required method for Designer support - do not modify /// the contents of this method with the code editor. ///

private void InitializeComponent() { this.Load += new System.EventHandler(this.Page_Load); } #endregion } }3.AjaxMethod using System; using System.Data; using System.Data.SqlClient; namespace AjaxTest { /**////

/// Summary description for AjaxMethod. ///

public class AjaxMethod { GetProvinceList#region GetProvinceList public static DataSet GetProvinceList() { string sql="select * from province"; return GetDataSet(sql); } #endregion GetCityList#region GetCityList [Ajax.AjaxMethod(Ajax.HttpSessionStateRequirement.Read)] public DataSet GetCityList(int provinceid) { string sql="select * from city where father="+provinceid; return GetDataSet(sql); } #endregion GetAreaList#region GetAreaList [Ajax.AjaxMethod(Ajax.HttpSessionStateRequirement.Read)] public DataSet GetAreaList(int cityid) { string sql="select * from area where father="+cityid; return GetDataSet(sql); } #endregion GetDataSet#region GetDataSet public static DataSet GetDataSet(string sql) { string ConnectionString=System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]; SqlDataAdapter sda =new SqlDataAdapter(sql,ConnectionString); DataSet ds=new DataSet(); sda.Fill(ds); return ds; } #endregion } }4.web.config type="Ajax.PageHandlerFactory, Ajax" />