再谈 N 个 ASP.net DropDownList 无刷新联动菜单，牺牲N-1个ASPX来实现自动更新机制，避免刷新的闪动！！
以下代码绝对可以使用，也可以实现多级菜单。。。。
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webform1.aspx
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(!IsPostBack)
{
SqlConnection con = new SqlConnection("packet size=4096;user id=sa;data source=SERVER;persist security info=False;initial catalog=pubs");
SqlDataAdapter da = new SqlDataAdapter("select state from authors group by state",con);
DataSet ds = new DataSet("State");
da.Fill(ds);
this.DropDownList1.DataSource = ds.Tables[0];
this.DropDownList1.DataTextField = "state";
this.DropDownList1.DataValueField = "state";
this.DropDownList1.DataBind();
this.DropDownList1.Attributes.Add("onchange","load()");
//DropDownList1.
}
}
webform2.aspx
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(this.Request["state"]!=null)
{
string state = this.Request["state"].ToString();
SqlConnection con = new SqlConnection("packet size=4096;user id=sa;data source=SERVER;persist security info=False;initial catalog=pubs");
SqlDataAdapter da = new SqlDataAdapter("select address from authors where state = '"+state+"'",con);
DataSet ds = new DataSet("address");
da.Fill(ds);
XmlTextWriter writer = new XmlTextWriter(Response.OutputStream, Response.ContentEncoding);
writer.Formatting = Formatting.Indented;
writer.Indentation = 4;
writer.IndentChar = ' ';
ds.WriteXml(writer);
writer.Flush();
Response.End();
writer.Close();
}
}