xmlconfigurator.cs

详细讲述了数据库编程

					
					// load the data into the document
					doc.Load(xmlReader);
				}
				catch(Exception ex)
				{
					LogLog.Error("XmlConfigurator: Error while loading XML configuration", ex);

					// The document is invalid
					doc = null;
				}

				if (doc != null)
				{
					LogLog.Debug("XmlConfigurator: loading XML configuration");

					// Configure using the 'log4net' element
					XmlNodeList configNodeList = doc.GetElementsByTagName("log4net");
					if (configNodeList.Count == 0)
					{
						LogLog.Debug("XmlConfigurator: XML configuration does not contain a <log4net> element. Configuration Aborted.");
					}
					else if (configNodeList.Count > 1)
					{
						LogLog.Error("XmlConfigurator: XML configuration contains [" + configNodeList.Count + "] <log4net> elements. Only one is allowed. Configuration Aborted.");
					}
					else
					{
						ConfigureFromXml(repository, configNodeList[0] as XmlElement);
					}
				}
			}
		}

		#endregion Configure static methods

		#region ConfigureAndWatch static methods

#if (!NETCF && !SSCLI)

		/// <summary>
		/// Configures log4net using the file specified, monitors the file for changes 
		/// and reloads the configuration if a change is detected.
		/// </summary>
		/// <param name="configFile">The XML file to load the configuration from.</param>
		/// <remarks>
		/// <para>
		/// The configuration file must be valid XML. It must contain
		/// at least one element called <c>log4net</c> that holds
		/// the configuration data.
		/// </para>
		/// <para>
		/// The configuration file will be monitored using a <see cref="FileSystemWatcher"/>
		/// and depends on the behavior of that class.
		/// </para>
		/// <para>
		/// For more information on how to configure log4net using
		/// a separate configuration file, see <see cref="Configure(FileInfo)"/>.
		/// </para>
		/// </remarks>
		/// <seealso cref="Configure(FileInfo)"/>
		static public void ConfigureAndWatch(FileInfo configFile)
		{
			ConfigureAndWatch(LogManager.GetRepository(Assembly.GetCallingAssembly()), configFile);
		}

		/// <summary>
		/// Configures the <see cref="ILoggerRepository"/> using the file specified, 
		/// monitors the file for changes and reloads the configuration if a change 
		/// is detected.
		/// </summary>
		/// <param name="repository">The repository to configure.</param>
		/// <param name="configFile">The XML file to load the configuration from.</param>
		/// <remarks>
		/// <para>
		/// The configuration file must be valid XML. It must contain
		/// at least one element called <c>log4net</c> that holds
		/// the configuration data.
		/// </para>
		/// <para>
		/// The configuration file will be monitored using a <see cref="FileSystemWatcher"/>
		/// and depends on the behavior of that class.
		/// </para>
		/// <para>
		/// For more information on how to configure log4net using
		/// a separate configuration file, see <see cref="Configure(FileInfo)"/>.
		/// </para>
		/// </remarks>
		/// <seealso cref="Configure(FileInfo)"/>
		static public void ConfigureAndWatch(ILoggerRepository repository, FileInfo configFile)
		{
			LogLog.Debug("XmlConfigurator: configuring repository [" + repository.Name + "] using file [" + configFile + "] watching for file updates");

			if (configFile == null)
			{
				LogLog.Error("XmlConfigurator: ConfigureAndWatch called with null 'configFile' parameter");
			}
			else
			{
				// Configure log4net now
				Configure(repository, configFile);

				try
				{
					// Create a watch handler that will reload the
					// configuration whenever the config file is modified.
					ConfigureAndWatchHandler.StartWatching(repository, configFile);
				}
				catch(Exception ex)
				{
					LogLog.Error("XmlConfigurator: Failed to initialize configuration file watcher for file ["+configFile.FullName+"]", ex);
				}
			}
		}
#endif

		#endregion ConfigureAndWatch static methods

		#region ConfigureAndWatchHandler

#if (!NETCF && !SSCLI)
		/// <summary>
		/// Class used to watch config files.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Uses the <see cref="FileSystemWatcher"/> to monitor
		/// changes to a specified file. Because multiple change notifications
		/// may be raised when the file is modified, a timer is used to
		/// compress the notifications into a single event. The timer
		/// waits for <see cref="TimeoutMillis"/> time before delivering
		/// the event notification. If any further <see cref="FileSystemWatcher"/>
		/// change notifications arrive while the timer is waiting it
		/// is reset and waits again for <see cref="TimeoutMillis"/> to
		/// elapse.
		/// </para>
		/// </remarks>
		private sealed class ConfigureAndWatchHandler
		{
			/// <summary>
			/// Watch a specified config file used to configure a repository
			/// </summary>
			/// <param name="repository">The repository to configure.</param>
			/// <param name="configFile">The configuration file to watch.</param>
			/// <remarks>
			/// <para>
			/// Watch a specified config file used to configure a repository
			/// </para>
			/// </remarks>
			internal static void StartWatching(ILoggerRepository repository, FileInfo configFile)
			{
				new ConfigureAndWatchHandler(repository, configFile);
			}

			/// <summary>
			/// Holds the FileInfo used to configure the XmlConfigurator
			/// </summary>
			private FileInfo m_configFile;

			/// <summary>
			/// Holds the repository being configured.
			/// </summary>
			private ILoggerRepository m_repository;

			/// <summary>
			/// The timer used to compress the notification events.
			/// </summary>
			private Timer m_timer;

			/// <summary>
			/// The default amount of time to wait after receiving notification
			/// before reloading the config file.
			/// </summary>
			private const int TimeoutMillis = 500;

			/// <summary>
			/// Initializes a new instance of the <see cref="ConfigureAndWatchHandler" /> class.
			/// </summary>
			/// <param name="repository">The repository to configure.</param>
			/// <param name="configFile">The configuration file to watch.</param>
			/// <remarks>
			/// <para>
			/// Initializes a new instance of the <see cref="ConfigureAndWatchHandler" /> class.
			/// </para>
			/// </remarks>
			private ConfigureAndWatchHandler(ILoggerRepository repository, FileInfo configFile)
			{
				m_repository = repository;
				m_configFile = configFile;

				// Create a new FileSystemWatcher and set its properties.
				FileSystemWatcher watcher = new FileSystemWatcher();

				watcher.Path = m_configFile.DirectoryName;
				watcher.Filter = m_configFile.Name;

				// Set the notification filters
				watcher.NotifyFilter = NotifyFilters.CreationTime | NotifyFilters.LastWrite | NotifyFilters.FileName;

				// Add event handlers. OnChanged will do for all event handlers that fire a FileSystemEventArgs
				watcher.Changed += new FileSystemEventHandler(ConfigureAndWatchHandler_OnChanged);
				watcher.Created += new FileSystemEventHandler(ConfigureAndWatchHandler_OnChanged);
				watcher.Deleted += new FileSystemEventHandler(ConfigureAndWatchHandler_OnChanged);
				watcher.Renamed += new RenamedEventHandler(ConfigureAndWatchHandler_OnRenamed);

				// Begin watching.
				watcher.EnableRaisingEvents = true;

				// Create the timer that will be used to deliver events. Set as disabled
				m_timer = new Timer(new TimerCallback(OnWatchedFileChange), null, Timeout.Infinite, Timeout.Infinite);
			}

			/// <summary>
			/// Event handler used by <see cref="ConfigureAndWatchHandler"/>.
			/// </summary>
			/// <param name="source">The <see cref="FileSystemWatcher"/> firing the event.</param>
			/// <param name="e">The argument indicates the file that caused the event to be fired.</param>
			/// <remarks>
			/// <para>
			/// This handler reloads the configuration from the file when the event is fired.
			/// </para>
			/// </remarks>
			private void ConfigureAndWatchHandler_OnChanged(object source, FileSystemEventArgs e)
			{
				LogLog.Debug("ConfigureAndWatchHandler: "+e.ChangeType+" [" + m_configFile.FullName + "]");

				// Deliver the event in TimeoutMillis time
				// timer will fire only once
				m_timer.Change(TimeoutMillis, Timeout.Infinite);
			}

			/// <summary>
			/// Event handler used by <see cref="ConfigureAndWatchHandler"/>.
			/// </summary>
			/// <param name="source">The <see cref="FileSystemWatcher"/> firing the event.</param>
			/// <param name="e">The argument indicates the file that caused the event to be fired.</param>
			/// <remarks>
			/// <para>
			/// This handler reloads the configuration from the file when the event is fired.
			/// </para>
			/// </remarks>
			private void ConfigureAndWatchHandler_OnRenamed(object source, RenamedEventArgs e)
			{
				LogLog.Debug("ConfigureAndWatchHandler: " + e.ChangeType + " [" + m_configFile.FullName + "]");

				// Deliver the event in TimeoutMillis time
				// timer will fire only once
				m_timer.Change(TimeoutMillis, Timeout.Infinite);
			}

			/// <summary>
			/// Called by the timer when the configuration has been updated.
			/// </summary>
			/// <param name="state">null</param>
			private void OnWatchedFileChange(object state)
			{
				XmlConfigurator.Configure(m_repository, m_configFile);
			}
		}
#endif

		#endregion ConfigureAndWatchHandler

		#region Private Static Methods

		/// <summary>
		/// Configures the specified repository using a <c>log4net</c> element.
		/// </summary>
		/// <param name="repository">The hierarchy to configure.</param>
		/// <param name="element">The element to parse.</param>
		/// <remarks>
		/// <para>
		/// Loads the log4net configuration from the XML element
		/// supplied as <paramref name="element"/>.
		/// </para>
		/// <para>
		/// This method is ultimately called by one of the Configure methods 
		/// to load the configuration from an <see cref="XmlElement"/>.
		/// </para>
		/// </remarks>
		static private void ConfigureFromXml(ILoggerRepository repository, XmlElement element) 
		{
			if (element == null)
			{
				LogLog.Error("XmlConfigurator: ConfigureFromXml called with null 'element' parameter");
			}
			else if (repository == null)
			{
				LogLog.Error("XmlConfigurator: ConfigureFromXml called with null 'repository' parameter");
			}
			else
			{
				LogLog.Debug("XmlConfigurator: Configuring Repository [" + repository.Name + "]");

				IXmlRepositoryConfigurator configurableRepository = repository as IXmlRepositoryConfigurator;
				if (configurableRepository == null)
				{
					LogLog.Warn("XmlConfigurator: Repository [" + repository + "] does not support the XmlConfigurator");
				}
				else
				{
					// Copy the xml data into the root of a new document
					// this isolates the xml config data from the rest of
					// the document
					XmlDocument newDoc = new XmlDocument();
					XmlElement newElement = (XmlElement)newDoc.AppendChild(newDoc.ImportNode(element, true));

					// Pass the configurator the config element
					configurableRepository.Configure(newElement);
				}			
			}
		}

		#endregion Private Static Methods
	}
}