App.Config操作

    public class ConfigUtils
    {
        public static string filename = System.Windows.Forms.Application.StartupPath + @"\App.config";
        /// <summary>
        /// 对[appSettings]节点依据Key值读取到Value值，返回字符串
        /// </summary>
        /// <param name="key">要读取的Key值</param>
        /// <returns>返回Value值的字符串</returns>
        public static string GetAppSetting(string key)
        {
            string value = null;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//appSettings");
            XmlElement element = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");
            if (element != null)
            {
                value = element.GetAttribute("value");
            }
            return value;
        }
        /// <summary>
        /// 对[connectionStrings]节点依据name值读取到connectionString值，返回字符串
        /// </summary>
        /// <param name="name">要读取的name值</param>
        /// <returns>返回connectionString值的字符串</returns>
        public static string GetConnectionString(string name)
        {
            string connectionString = null;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//connectionStrings");
            XmlElement element = (XmlElement)node.SelectSingleNode("//add[@name='" + name + "']");
            if (element != null)
            {
                connectionString = element.GetAttribute("connectionString");
            }
            return connectionString;
        }
        /// <summary>
        /// 更新或新增[appSettings]节点的子节点值，存在则更新子节点Value,不存在则新增子节点，返回成功与否布尔值
        /// </summary>
        /// <param name="key">子节点Key值</param>
        /// <param name="value">子节点value值</param>
        /// <returns>返回成功与否布尔值</returns>
        public static bool SetAppSetting(string key, string value)
        {
            bool isSuccess = false;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//appSettings");
            try
            {
                if (node == null)
                {
                    //不存在则新增appSettings子节点
                    XmlNode root = doc.DocumentElement;
                    XmlElement appElement = doc.CreateElement("appSettings");
                    XmlElement subElement = doc.CreateElement("add");
                    subElement.SetAttribute("key", key);
                    subElement.SetAttribute("value", value);
                    appElement.AppendChild(subElement);
                    root.AppendChild(appElement);
                }
                else
                {
                    XmlElement element = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");
                    if (element != null)
                    {
                        //存在则更新子节点Value
                        element.SetAttribute("value", value);
                    }
                    else
                    {
                        //不存在则新增子节点
                        XmlElement subElement = doc.CreateElement("add");
                        subElement.SetAttribute("key", key);
                        subElement.SetAttribute("value", value);
                        node.AppendChild(subElement);
                    }
                }
                using (XmlTextWriter xmlwriter = new XmlTextWriter(filename, null))
                {
                    xmlwriter.Formatting = Formatting.Indented;
                    doc.WriteTo(xmlwriter);
                    xmlwriter.Flush();
                }
                isSuccess = true;
            }
            catch (Exception e)
            {
                isSuccess = false;
            }
            return isSuccess;
        }
        /// <summary>
        /// 更新或新增[connectionStrings]节点的子节点值，存在则更新子节点,不存在则新增子节点，返回成功与否布尔值
        /// </summary>
        /// <param name="name">子节点name值</param>
        /// <param name="connectionString">子节点connectionString值</param>
        /// <param name="providerName">子节点providerName值</param>
        /// <returns>返回成功与否布尔值</returns>
        public static bool SetConnectionString(string name, string connectionString, string providerName)
        {
            bool isSuccess = false;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//connectionStrings");
            try
            {
                if (node == null)
                {
                    //不存在则新增connectionStrings子节点
                    XmlNode root = doc.DocumentElement;
                    XmlElement connElement = doc.CreateElement("connectionStrings");
                    XmlElement subElement = doc.CreateElement("add");
                    subElement.SetAttribute("name", name);
                    subElement.SetAttribute("connectionString", connectionString);
                    subElement.SetAttribute("providerName", providerName);
                    connElement.AppendChild(subElement);
                    root.AppendChild(connElement);
                }
                else
                {
                    XmlElement element = (XmlElement)node.SelectSingleNode("//add[@name='" + name + "']");
                    if (element != null)
                    {
                        //存在则更新子节点
                        element.SetAttribute("connectionString", connectionString);
                        element.SetAttribute("providerName", providerName);
                    }
                    else
                    {
                        //不存在则新增子节点
                        XmlElement subElement = doc.CreateElement("add");
                        subElement.SetAttribute("name", name);
                        subElement.SetAttribute("connectionString", connectionString);
                        subElement.SetAttribute("providerName", providerName);
                        node.AppendChild(subElement);
                    }
                }
                doc.Save(filename);
                isSuccess = true;
            }
            catch (Exception e)
            {
                isSuccess = false;
            }
            return isSuccess;
        }
        /// <summary>
        /// 更新或新增[connectionStrings]节点的子节点值，存在则更新子节点,不存在则新增子节点，返回成功与否布尔值
        /// </summary>
        /// <param name="name">子节点name值</param>
        /// <param name="connectionString">子节点connectionString值</param>
        /// <param name="providerName">子节点providerName值</param>
        /// <returns>返回成功与否布尔值</returns>
        public static bool SetConnectionString(string name, string connectionString)
        {
            bool isSuccess = false;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//connectionStrings");
            try
            {
                if (node == null)
                {
                    //不存在则新增connectionStrings子节点
                    XmlNode root = doc.DocumentElement;
                    XmlElement connElement = doc.CreateElement("connectionStrings");
                    XmlElement subElement = doc.CreateElement("add");
                    subElement.SetAttribute("name", name);
                    subElement.SetAttribute("connectionString", connectionString);
                    connElement.AppendChild(subElement);
                    root.AppendChild(connElement);
                }
                else
                {
                    XmlElement element = (XmlElement)node.SelectSingleNode("//add[@name='" + name + "']");
                    if (element != null)
                    {
                        //存在则更新子节点
                        element.SetAttribute("connectionString", connectionString);
                    }
                    else
                    {
                        //不存在则新增子节点
                        XmlElement subElement = doc.CreateElement("add");
                        subElement.SetAttribute("name", name);
                        subElement.SetAttribute("connectionString", connectionString);
                        node.AppendChild(subElement);
                    }
                }
                doc.Save(filename);
                isSuccess = true;
            }
            catch (Exception e)
            {
                isSuccess = false;
            }
            return isSuccess;
        }

        /// <summary>
        /// 删除[appSettings]节点中包含Key值的子节点，返回成功与否布尔值
        /// </summary>
        /// <param name="key">要删除的子节点Key值</param>
        /// <returns>返回成功与否布尔值</returns>
        public static bool DeleteAppSetting(string key)
        {
            bool isSuccess = false;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//appSettings");
            XmlElement element = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");
            if (element != null)
            {
                //存在则删除子节点
                element.ParentNode.RemoveChild(element);
            }
            try
            {
                using (XmlTextWriter xmlwriter = new XmlTextWriter(filename, null))
                {
                    xmlwriter.Formatting = Formatting.Indented;
                    doc.WriteTo(xmlwriter);
                    xmlwriter.Flush();
                }
                isSuccess = true;
            }
            catch (Exception e)
            {
                isSuccess = false;
            }
            return isSuccess;
        }
        /// <summary>
        /// 删除[connectionStrings]节点中包含name值的子节点，返回成功与否布尔值
        /// </summary>
        /// <param name="name">要删除的子节点name值</param>
        /// <returns>返回成功与否布尔值</returns>
        public static bool DeleteConnectionString(string name)
        {
            bool isSuccess = false;
            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNode node = doc.SelectSingleNode("//connectionStrings");
            XmlElement element = (XmlElement)node.SelectSingleNode("//add[@name='" + name + "']");
            if (element != null)
            {
                //存在则删除子节点
                node.RemoveChild(element);
            }

            try
            {
                doc.Save(filename);
                isSuccess = true;
            }
            catch (Exception e)
            {
                isSuccess = false;
            }
            return isSuccess;
        }
    }

    class SetConfig
    {
        /// <summary>
        /// 对[appSettings]节点依据Key值读取到Value值
        /// </summary>
        /// <param name="strKey"></param>
        /// <returns></returns>
        public static string GetAppSettings(string strKey)
        {
            foreach (string key in ConfigurationManager.AppSettings)
            {
                if (key == strKey)
                {
                    return ConfigurationManager.AppSettings[strKey];
                }
            }
            return null;
        }
        /// <summary>
        /// 更新或新增[appSettings]节点的子节点值
        /// </summary>
        /// <param name="newKey"></param>
        /// <param name="newValue"></param>
        public static void SetAppSettings(string newKey, string newValue)
        {
            bool isModified = false;
            // 如果要更改的Key已经存在
            foreach (string key in ConfigurationManager.AppSettings)
            {
                if (key == newKey)
                {
                    isModified = true;
                }
            }
            //打开 App.Config
            Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            // 如果连接串已存在，首先删除它
            if (isModified)
            {
                config.AppSettings.Settings.Remove(newKey);
            }
            //添加新的配置到配置文件里
            config.AppSettings.Settings.Add(newKey, newValue);
            //保存对配置节所做的更改
            config.Save(ConfigurationSaveMode.Modified);
            //强制重载配置节
            ConfigurationManager.RefreshSection("appSettings");
        }
        /// <summary>
        /// 对[connectionStrings]节点依据name值读取
        /// </summary>
        /// <param name="strName"></param>
        /// <returns></returns>
        public static string GetConnectionString(string strName)
        {
            foreach (ConnectionStringSettings item in ConfigurationManager.ConnectionStrings)
            {
                if (item.Name == strName)
                {
                    return ConfigurationManager.ConnectionStrings[strName].ConnectionString;
                }
            }
            return null;
        }
        /// <summary>
        /// 更新或新增[connectionStrings]节点的子节点值
        /// </summary>
        /// <param name="newName"></param>
        /// <param name="newValue"></param>
        public static void SetConnectionString(string newName, string newValue)
        {
            bool isModified = false;
            // 如果要更改的Key已经存在
            foreach (ConnectionStringSettings item in ConfigurationManager.ConnectionStrings)
            {
                if (item.Name == newName)
                {
                    isModified = true;
                }
            }
            //打开 App.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);
            }
            //添加新的配置到配置文件里
            ConnectionStringSettings conSetting = new ConnectionStringSettings(newName, newValue);
            config.ConnectionStrings.ConnectionStrings.Add(conSetting);
            //保存对配置节所做的更改
            config.Save(ConfigurationSaveMode.Modified);
            //强制重载配置节
            ConfigurationManager.RefreshSection("connectionStrings");
        }

    }