XML内容如下：
复制代码 代码如下:
<?xml version="1.0" encoding="utf-8" ?>
<SystemVersion>
<Item>
<Version_ID>1</Version_ID>
<Version_Name>CN</Version_Name>
</Item>
<Item>
<Version_ID>2</Version_ID>
<Version_Name>EN</Version_Name>
</Item>
</SystemVersion>

用户控件的关键代码：
SystemVersion.ascx
复制代码 代码如下:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="SystemVersion.ascx.cs" Inherits="UserControls_SystemVersion" %>
<!-- Value是传入的值 -->
<div style="white-space:nowrap">
<asp:DropDownList ID="ddlVersion" runat="server">
</asp:DropDownList>
</div>

后台文件：
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Xml;
using System.Xml.Linq;

public partial class UserControls_SystemVersion : System.Web.UI.UserControl
{
private const string CON_FilePath = "~/App_Data/sysVersion.xml";

//// <summary>
/// 下拉框赋值
/// </summary>
public string Value
{
set { ViewState["Value"] = value; }
get { return ViewState["Value"] == null ? null : ViewState["Value"].ToString().Trim(); }
}

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DdlBind();
}
}

public void DdlBind()
{
XElement xDoc = XElement.Load(Server.MapPath(CON_FilePath));

// Create the query
var lVersion = from c in xDoc.Descendants("Item")
where c.Element("Version_ID").Value == "1" //目前只显示CN
select new
{
Version_Name = c.Element("Version_Name").Value,
Version_ID = c.Element("Version_ID").Value
};

ddlVersion.DataSource = lVersion.ToList();
ddlVersion.DataTextField = "Version_Name";
ddlVersion.DataValueField = "Version_Name";
ddlVersion.DataBind();
if (Value != null)
{
ddlVersion.SelectedValue=Value;
}
}
}