1.建立一个class，ReadWriteConfig.cs
using System;using System.Configuration;using System.Reflection;using System.Web;using System.Xml;public enum ConfigFileType
{
WebConfig, AppConfig
}namespace WebApplication1{
/**//// <summary> /// Summary description for ReadWriteConfig.
/// </summary> public class ReadWriteConfig { public string docName = String.Empty; private XmlNode node=null; private int _configType; public int ConfigType { get{ return _configType; } set{ _configType=value; } } SetValue#region SetValue public bool SetValue(string key, string value) { XmlDocument cfgDoc = new XmlDocument(); loadConfigDoc(cfgDoc); // retrieve the appSettings node node = cfgDoc.SelectSingleNode("//appSettings"); if( node == null ) { throw new InvalidOperationException( "appSettings section not found"); } try { // XPath select setting "add" element that contains this key XmlElement addElem= (XmlElement)node.SelectSingleNode("//add[@key='" +key +"']") ; if(addElem!=null) { addElem.SetAttribute("value",value); } // not found, so we need to add the element, key and value else { XmlElement entry = cfgDoc.CreateElement("add"); entry.SetAttribute("key",key); entry.SetAttribute("value",value); node.AppendChild(entry); } //save it saveConfigDoc(cfgDoc,docName); return true; } catch { return false; } } #endregion saveConfigDoc#region saveConfigDoc private void saveConfigDoc(XmlDocument cfgDoc,string cfgDocPath) { try { XmlTextWriter writer = new XmlTextWriter( cfgDocPath , null ); writer.Formatting = Formatting.Indented; cfgDoc.WriteTo( writer ); writer.Flush(); writer.Close(); return; } catch { throw; } } #endregion removeElement#region removeElement public bool removeElement (string elementKey) { try { XmlDocument cfgDoc = new XmlDocument(); loadConfigDoc(cfgDoc); // retrieve the appSettings node node = cfgDoc.SelectSingleNode("//appSettings"); if( node == null ) { throw new InvalidOperationException( "appSettings section not found"); } // XPath select setting "add" element that contains this key to remove node.RemoveChild( node.SelectSingleNode("//add[@key='" +elementKey +"']") ); saveConfigDoc(cfgDoc,docName); return true; } catch { return false; } } #endregion modifyElement#region modifyElement public bool modifyElement (string elementKey) { try { XmlDocument cfgDoc = new XmlDocument(); loadConfigDoc(cfgDoc); // retrieve the appSettings node node = cfgDoc.SelectSingleNode("//appSettings"); if( node == null ) { throw new InvalidOperationException( "appSettings section not found"); } // XPath select setting "add" element that contains this key to remove node.RemoveChild(node.SelectSingleNode("//add[@key='" +elementKey +"']")); saveConfigDoc(cfgDoc,docName); return true; } catch { return false; } } #endregion loadConfigDoc#region loadConfigDoc private XmlDocument loadConfigDoc( XmlDocument cfgDoc ) { // load the config file if( Convert.ToInt32(ConfigType)==