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();
            }
        }