对WEB.Config文件进行（读写操作）

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;
using System.Xml;

namespace simx
{
    /**//// <summary>
    /// WebForm1 的摘要说明。
    /// </summary>
    public class WebForm1 : System.Web.UI.Page
    {
        private void Page_Load(object sender, System.EventArgs e)
        {
            if(!Page.IsPostBack)
            {
                read();
            }
        }
        public void read()  //读Web.config
        {
            string filename=Server.MapPath("")+@"Web.config";
            XmlDocument xmldoc=new XmlDocument();
            xmldoc.Load(filename);
            XmlNodeList topM=xmldoc.DocumentElement.ChildNodes;
            foreach(XmlElement element in topM)
            {
              //判断是否存在<appSettings>配置节
                if(element.Name=="appSettings")
                {
                   XmlNodeList node=element.ChildNodes;
                    if(node.Count>0)
                    {
                       DropDownList1.Items.Clear();
                        foreach(XmlElement el in node)
                        {
                          DropDownList1.Items.Add(el.Attributes["key"].InnerXml);
                        }
                    }
                }
            }
        }
        public void write()   //写Web.config
        {
           string filename=Server.MapPath("")+@"Web.config";
           XmlDocument xmldoc=new XmlDocument();
           xmldoc.Load(filename);
           XmlNodeList topM=xmldoc.DocumentElement.ChildNodes;
            foreach(XmlElement element in topM)
            {
                //判断是否存在<appsettings>配置节
                if(element.Name=="appsettings")
                {
                  XmlNodeList node=element.ChildNodes;
                    if(node.Count>0)
                    {
                        foreach(XmlElement el in node)
                        {
                            if(el.Attributes["key"].InnerXml.ToLower()==this.DropDownList1.SelectedItem.Value.ToLower())
                            {
                              el.Attributes["key"].Value=this.TextBox1.Text;
                            }
                        }
                    }
                }
            }
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
       
        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {   
            this.Load += new System.EventHandler(this.Page_Load);
        }
        #endregion
    }
}