using System;

using System.Configuration;

using System.Web;

using System.Web.Configuration;

namespace Whir.ezEIP

{

    ///

    /// WebConfig讀寫輔助類

    ///

    public class WebConfigManager : IDisposable

    {

        private Configuration _config;

        ///

        /// WebConfig讀寫輔助類

        ///

        public WebConfigManager()

            : this(HttpContext.Current.Request.ApplicationPath)

        {

        }

        ///

        /// WebConfig讀寫輔助類

        ///

        ///

        public WebConfigManager(string path)

        {

            _config = WebConfigurationManager.OpenWebConfiguration(path);

        }

        #region IDisposable Members

        public void Dispose()

        {

            if (_config != null)

            {

                _config.Save();

            }

        }

        #endregion

        /// 

        /// 設置應用程序配置節(jié)點，如果已經(jīng)存在此節(jié)點，則會修改該節(jié)點的值，否則添加此節(jié)點

        /// 

        /// 節(jié)點名稱

        /// 節(jié)點值

        public void SetAppSetting(string key, string value)

        {

            var appSetting = (AppSettingsSection)_config.GetSection("appSettings");

            if (appSetting.Settings[key] == null) //如果不存在此節(jié)點，則添加

            {

                appSetting.Settings.Add(key, value);

            }

            else //如果存在此節(jié)點，則修改

            {

                appSetting.Settings[key].Value = value;

            }

            Save();

        }

        /// 

        /// 設置數(shù)據(jù)庫連接字符串節(jié)點，如果不存在此節(jié)點，則會添加此節(jié)點及對應的值，存在則修改

        /// 

        /// 節(jié)點名稱

        /// 

        public void SetConnectionString(string key, string connectionString)

        {

            var connectionSetting = (ConnectionStringsSection)_config.GetSection("connectionStrings");

            if (connectionSetting.ConnectionStrings[key] == null) //如果不存在此節(jié)點，則添加

            {

                var connectionStringSettings = new ConnectionStringSettings(key, connectionString);

                connectionSetting.ConnectionStrings.Add(connectionStringSettings);

            }

            else //如果存在此節(jié)點，則修改

            {

                connectionSetting.ConnectionStrings[key].ConnectionString = connectionString;

            }

            Save();

        }

        /// 

        /// 保存所作的修改

        /// 

        public void Save()

        {

            _config.Save();

            _config = null;

        }

    }

}

使用方法：

 var config = new WebConfigManager();
config.SetAppSetting("StrRegex", "");

讀取AppSetting和ConnectionString：

string fileType=ConfigurationManager.AppSettings["FileType "];

string connectionString = ConfigurationManager.ConnectionStrings["AspNetStudyConnectionString1"].ConnectionString;