/BlogEngine/DotNetSlave.BusinessLogic/Web/AppConfig.cs

using System;

using System.Configuration;

using System.IO;

using System.Web;

using System.Xml;



namespace BlogEngine.Core.Web

{

    /// <summary>

    /// 

    /// </summary>

    public class AppConfig : AppSettingsReader

    {

        private XmlDocument cfgDoc = new XmlDocument();

        public string docName = "web.config";

        private XmlNode node = null;



        /// <summary>

        /// 

        /// </summary>

        /// <returns></returns>

        public static AppConfig Instance()

        {

            return new AppConfig();

        }



        /// <summary>

        /// 

        /// </summary>

        /// <param name="key"></param>

        /// <param name="value"></param>

        /// <returns></returns>

        public bool SetValue(string key, string value)

        {

            object _lock = new object();





            lock (_lock)

            {

                loadConfigDoc();

                // retrieve the appSettings node 

                node = cfgDoc.SelectSingleNode("//appSettings");



                if (node == null)

                {

                    throw new InvalidOperationException("appSettings section not found");

                }



                try

                {

                    // XPath select setting "add" element that contains this key    

                    XmlElement addElem = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");

                    if (addElem != null)

                    {

                        addElem.SetAttribute("value", value);

                    }

                    // not found, so we need to add the element, key and value

                    else

                    {

                        XmlElement entry = cfgDoc.CreateElement("add");

                        entry.SetAttribute("key", key);

                        entry.SetAttribute("value", value);

                        node.AppendChild(entry);

                    }

                    //save it

                    saveConfigDoc(docName);

                    return true;

                }

                catch

                {

                    return false;

                }

            }

        }



        /// <summary>

        /// 

        /// </summary>

        /// <param name="cfgDocPath"></param>

        private void saveConfigDoc(string cfgDocPath)

        {

            try

            {

                XmlTextWriter writer = new XmlTextWriter(cfgDocPath, null);

                writer.Formatting = Formatting.Indented;

                cfgDoc.WriteTo(writer);

                writer.Flush();

                writer.Close();

                return;

            }

            catch (Exception e)

            {

                throw new FileLoadException("Unable to load the web.config file for modification", e.InnerException);

            }

        }



        /// <summary>

        /// 

        /// </summary>

        /// <param name="elementKey"></param>

        /// <returns></returns>

        public bool removeElement(string elementKey)

        {

            try

            {

                loadConfigDoc();

                // retrieve the appSettings node 

                node = cfgDoc.SelectSingleNode("//appSettings");

                if (node == null)

                {

                    throw new InvalidOperationException("appSettings section not found");

                }

                // XPath select setting "add" element that contains this key to remove   

                node.RemoveChild(node.SelectSingleNode("//add[@key='" + elementKey + "']"));



                saveConfigDoc(docName);

                return true;

            }

            catch

            {

                return false;

            }

        }



        /// <summary>

        /// 

        /// </summary>

        /// <returns></returns>

        private void loadConfigDoc()

        {

            // load the config file 

            docName = HttpContext.Current.Server.MapPath(docName);

            cfgDoc.Load(docName);

            return;

        }

    }

}