winform开发中对App.Config的写和读操作

using System;

using System.Configuration;

using System.Collections.Generic;

using System.Text;

using System.Xml;

using System.Web;

using System.Reflection;



namespace Common

{

    /// <summary>

    /// 配置文件类型,是WinForm还是WebForm

    /// </summary>

    public enum ConfigFileType

    {

        WebConfig,

        AppConfig

    }

    /// <summary>

    /// 对AppSettings节点进行增加，删除，修改操作.

    /// </summary>

    public class AppSettingsHelper

    {

        public static string docName = String.Empty;

        private static XmlNode node = null;





        /// <summary>

        /// 设置节点的值，若该节点不存在，则创建一个新的节点。

        /// </summary>

        /// <param name="key"></param>

        /// <param name="value"></param>

        /// <param name="cfgType"></param>

        /// <returns></returns>

        public static bool SetValue(string key, string value, ConfigFileType cfgType)

        {

            XmlDocument cfgDoc = new XmlDocument();

            loadConfigDoc(cfgDoc, cfgType);

            // 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;

            }

        }

        /// <summary>

        /// 获取节点的值

        /// </summary>

        /// <param name="key"></param>

        /// <param name="cfgType"></param>

        /// <returns></returns>

        public static string GetValue(string key, ConfigFileType cfgType)

        {

            XmlDocument cfgDoc = new XmlDocument();

            loadConfigDoc(cfgDoc, cfgType);

            // 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       

            XmlElement addElem = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");

            if (addElem != null)

            {



                return addElem.GetAttribute("value");

            }

            // not found, so we need to add the element, key and value   

            else

            {

                throw new ArgumentException(string.Format("key '{0}' not found", key));

            }





        }





        private static 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;

            }

        }







        /// <summary>

        /// 移除节点

        /// </summary>

        /// <param name="elementKey"></param>

        /// <param name="cfgType"></param>

        /// <returns></returns>

        public static bool RemoveElement(string elementKey, ConfigFileType cfgType)

        {

            try

            {

                XmlDocument cfgDoc = new XmlDocument();

                loadConfigDoc(cfgDoc, cfgType);

                // 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;

            }

        }





        /// <summary>

        /// 修改节点的值

        /// </summary>

        /// <param name="elementKey"></param>

        /// <param name="cfgType"></param>

        /// <returns></returns>

        public static bool ModifyElement(string elementKey, ConfigFileType cfgType)

        {

            try

            {

                XmlDocument cfgDoc = new XmlDocument();

                loadConfigDoc(cfgDoc, cfgType);

                // 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;

            }

        }







        private static XmlDocument loadConfigDoc(XmlDocument cfgDoc, ConfigFileType cfgType)

        {

            // load the config file   

            if (cfgType == ConfigFileType.AppConfig)

            {

                docName = ((Assembly.GetEntryAssembly()).GetName()).Name;

                docName += ".exe.config";

            }

            else

            {

                docName = HttpContext.Current.Server.MapPath("web.config");

            }

            cfgDoc.Load(docName);

            return cfgDoc;

        }



    }

}

            Configuration C=ConfigurationManager.OpenExeConfiguration(String .Empty);   

            C.AppSettings.Settings["Server"].Value = "192.168.1.11";

            C.AppSettings.Settings["Database"].Value = "aaa";

            C.AppSettings.Settings["Uid"].Value = "sa";

            C.AppSettings.Settings["Pwd"].Value = "123";

            C.Save(ConfigurationSaveMode.Modified);