读取、添加、删除、修改配置文件 如（Web.config, App.config)

    private Configuration config;
         public OperateConfig()
             : this(HttpContext.Current.Request.ApplicationPath)
         {
         }

         public OperateConfig(string path)
         {
             config = WebConfigurationManager.OpenWebConfiguration(path);
         }

         /// <summary>
         /// 设置应用程序配置节点,如果已经存在此节点,则会修改该节点的值,否则添加此节点
         /// </summary>
         /// <param name="key"></param>
         /// <param name="value"></param>
         public void SetAppSetting(string key, string value)
         {
             AppSettingsSection appSetting = (AppSettingsSection)config.GetSection("appSettings");
             if (appSetting.Settings[key] == null)
             {
                 appSetting.Settings.Add(key, value);
             }
             else
             {
                 appSetting.Settings[key].Value = value;
             }
         }

         /// <summary>
         /// 设置数据库连接字符串节点,如果不存在此节点,则会添加此节点及对应的值,存在则修改
         /// </summary>
         /// <param name="key"></param>
         /// <param name="connectionString"></param>
         public void SetConnectionString(string key, string connectionString)
         {
             ConnectionStringsSection connectionSetting = (ConnectionStringsSection)config.GetSection("connectionStrings");
             if (connectionSetting.ConnectionStrings[key] == null)//如果不存在此节点,则添加
             {
                 ConnectionStringSettings connectionStringSettings = new ConnectionStringSettings(key, connectionString);
                 connectionSetting.ConnectionStrings.Add(connectionStringSettings);
             }
             else//如果存在此节点,则修改
             {
                 connectionSetting.ConnectionStrings[key].ConnectionString = connectionString;
             }
         }

         /// <summary>
         /// 保存所作的修改
         /// </summary>
         public void Save()
         {
             config.Save();
             config = null;
         }

         public void Dispose()
         {
             if (config != null)
             {
                 config.Save();
             }
         }