public class AppModify    {        /// 
        /// 依据连接串名字connectionName返回数据连接字符串        /// 
        ///         /// 
             public static string GetConnectionStringsConfig(string connectionName)        {            string connectionString =                    ConfigurationManager.ConnectionStrings[connectionName].ConnectionString.ToString();            return connectionString;        }        /// 
        /// 更新连接字符串        /// 
        ///  连接字符串名称         ///  连接字符串内容         ///  数据提供程序名称         public static void UpdateConnectionStringsConfig(string newName,            string newConString,            string newProviderName)        {            bool isModified = false;    // 记录该连接串是否已经存在            // 如果要更改的连接串已经存在            if (ConfigurationManager.ConnectionStrings[newName] != null)            {                isModified = true;            }            // 新建一个连接字符串实例            ConnectionStringSettings mySettings =                new ConnectionStringSettings(newName, newConString, newProviderName);            // 打开可执行的配置文件*.exe.config            Configuration config =                ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);            // 如果连接串已存在，首先删除它            if (isModified)            {                config.ConnectionStrings.ConnectionStrings.Remove(newName);            }            // 将新的连接串添加到配置文件中.            config.ConnectionStrings.ConnectionStrings.Add(mySettings);            // 保存对配置文件所作的更改            config.Save(ConfigurationSaveMode.Modified);            // 强制重新载入配置文件的ConnectionStrings配置节            ConfigurationManager.RefreshSection("ConnectionStrings");        }        public static void UpdateConnectionStringsConfig(string newName,           string newConString)        {            bool isModified = false;    // 记录该连接串是否已经存在            // 如果要更改的连接串已经存在            if (ConfigurationManager.ConnectionStrings[newName] != null)            {                isModified = true;            }            // 新建一个连接字符串实例            ConnectionStringSettings mySettings =                new ConnectionStringSettings(newName, newConString);            // 打开可执行的配置文件*.exe.config            Configuration config =                ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);            // 如果连接串已存在，首先删除它            if (isModified)            {                config.ConnectionStrings.ConnectionStrings.Remove(newName);            }            // 将新的连接串添加到配置文件中.            config.ConnectionStrings.ConnectionStrings.Add(mySettings);            // 保存对配置文件所作的更改            config.Save(ConfigurationSaveMode.Modified);            // 强制重新载入配置文件的ConnectionStrings配置节            ConfigurationManager.RefreshSection("ConnectionStrings");        }        /// 
        /// 返回＊.exe.config文件中appSettings配置节的value项        /// 
        ///         /// 
             public static string GetAppConfig(string strKey)        {            foreach (string key in ConfigurationManager.AppSettings)            {                if (key == strKey)                {                    return ConfigurationManager.AppSettings[strKey];                }            }            return null;        }        /// 
        /// 在＊.exe.config文件中appSettings配置节增加一对键、值对        /// 
        ///         ///         public static void UpdateAppConfig(string newKey, string newValue)        {            bool isModified = false;            foreach (string key in ConfigurationManager.AppSettings)            {                if (key == newKey)                {                    isModified = true;                }            }            // Open App.Config of executable            Configuration config =                ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);            // You need to remove the old settings object before you can replace it            if (isModified)            {                config.AppSettings.Settings.Remove(newKey);            }            // Add an Application Setting.            config.AppSettings.Settings.Add(newKey, newValue);            // Save the changes in App.config file.            config.Save(ConfigurationSaveMode.Modified);            // Force a reload of a changed section.            ConfigurationManager.RefreshSection("appSettings");        }    }