再谈N个ASP.net DropDownList无刷新联动菜单

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。。。。

function load(state)

{

var drp2 = document.getElementById("DropDownList2");

for(var i=0;i<=drp2.options.length-1;i++)

{

drp2.remove(i);

}

var oHttpReq = new ActiveXObject("MSXML2.XMLHTTP"); //发送请求

var oDoc = new ActiveXObject("MSXML2.DOMDocument"); //响应结果

var state=document.getElementById("DropDownList1").value;

oHttpReq.open("post","webform2.aspx?state="+state, false);

oHttpReq.send("");

result = oHttpReq.responseText;

oDoc.loadXML(result);

// items = oDoc.selectNodes("//CITY/Table");

items = oDoc.selectNodes("//address/Table");

for (var item = items.nextNode();item;item = items.nextNode())

{

var city = item.selectSingleNode("//address").nodeTypedValue;

var newOption = document.createElement("OPTION");

newOption.text = city;

newOption.value = city;

drp2.options.add(newOption);

}

</script>

============================

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();

}