在 log4net 中以编程方式更改日志级别？

Question

Is there a way to set the log level in log4net programmatically? I'd assumed that there would be a property that would let you do this, but I can't seem to find one.

What I want to do is have a configurable option to enter debug mode. which would cause extra logging.

I'm using a separate log4net configuration xml file. At the moment the solutions I've come up with are as follows:

1. Edit the log file using the dom and then call XMLConfigurator to configure the log file as per the file.

2. Have two log configuration files, and on the option changing call xml Configurator to use the appropriate log configuration file.

I'm leaning towards 2, is there any reason this wont work?

Answer 1

You can programmatically change the Logging level of a log4net logger, but it's not obvious how to do so. I have some code that does this. Given this Logger:

private readonly log4net.ILog mylogger;

You have to do the following fancy footwork to set it to Debug:

((log4net.Repository.Hierarchy.Logger)mylogger.Logger).Level = log4net.Core.Level.Debug;

Answer 2

This is the way I'm configuring log4net programmatically:

//declared as a class variable   
private static readonly ILog logger = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

 PatternLayout layout = new PatternLayout(@"%date %-5level %message%newline");
    RollingFileAppender appender = new RollingFileAppender();
    appender.Layout = layout;
    appender.File = "c:\log.txt";
    appender.AppendToFile = true;
    appender.MaximumFileSize = "1MB";
    appender.MaxSizeRollBackups = 0; //no backup files
    appender.Threshold = Level.Error;
    appender.ActivateOptions();                       
    log4net.Config.BasicConfigurator.Configure(appender);

I think the Appender's Threshold property is what you looking for, it will control what levels of logging the appender will output.

The log4net manual has lots of good configuration examples.

Answer 3

This is a follow up to your comment on Mitch's answer.

While you may be able to set the levels programmaticaly, why not just set the log levels to debug? That way your user will not have to worry about setting the log levels to debug, which, trust me, will never be on when you need it.

Then when an error occurs, just have the user send you the full log file and use a log viewer like Apache Chainsaw to selectively view only the levels you want to see.

Another solution is to log the different levels to separate files. That way you can have the user send you only the levels that you want to see.

Answer 4

You could download the sample project from here or copy paste the code bellow. At the end of the code is the DDL SQL for the table holding the logging info..

  using System;
  using System.Collections.Generic;
  using System.Text;
  using log4net;
  using log4net.Config;
  using NUnit.Framework;
  using GenApp.Utils; 

  namespace ExampleConsoleApplication
  {


    class TestClass
    {

        private static readonly ILog logger =
                 LogManager.GetLogger ( typeof ( TestClass ) );


        static void Main ( string[] args )
        {
        TestClass objTestClass = new TestClass ();
  //log4net.Appender.ColoredConsoleAppender.Colors.HighIntensity
        GenApp.Bo.UserSettings us = new GenApp.Bo.UserSettings ();
        GenApp.Bo.User userObj = new GenApp.Bo.User ()
        {

          UserSettings = us

        };
        userObj.UserSettings.LogLevel = 4; 




        #region SetDynamicallyLogLevel


        Logger.Debug ( userObj, logger, " -- Debug msg -- " );
        Logger.Info ( userObj, logger, " -- Info msg -- " );
        Logger.Warn ( userObj, logger, " -- Warn msg -- " );
        Logger.Error ( userObj, logger, " -- Error msg -- " );
        Logger.Fatal ( userObj, logger, " -- Fatal msg -- " );
        #endregion SetDynamicallyLogLevel



        #region RemoveDynamicallyAppenders
        Logger.SetThreshold ( "LogFileAppender", log4net.Core.Level.Off );

        //and echo again
        Logger.Debug ( userObj, logger, " -- Debug msg -- " );
        Logger.Info ( userObj, logger, " -- Info msg -- " );
        Logger.Warn ( userObj, logger, " -- Warn msg -- " );
        Logger.Error ( userObj, logger, " -- Error msg -- " );
        Logger.Fatal ( userObj, logger, " -- Fatal msg -- " );



        #endregion RemoveDynamicallyAppenders

        Console.WriteLine ( " END HIT A KEY TO EXIT " );
            Console.ReadLine ();
            } //eof method 


    } //eof class 

  } //eof namespace 




  /* App.config CopyPaste 
  <?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
  <section name="log4net"
       type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>

<log4net>
  <appender name="LogFileAppender" type="log4net.Appender.FileAppender">
    <param name="File" value="Program.log" />
    <param name="AppendToFile" value="true" />
    <layout type="log4net.Layout.PatternLayout">
      <!--<param name="Header" value="======================================" />
      <param name="Footer" value="======================================" />-->
      <param name="ConversionPattern" value="%date{yyyy'.'MM'.'dd --- HH':'mm':'ss'.'fff} [%t] %-5p -- %m%n" />
    </layout>
  </appender>

  <appender name="ColoredConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
    <mapping>
      <level value="ERROR" />
      <foreColor value="Red" />
    </mapping>
    <mapping>
      <level value="DEBUG" />
      <foreColor value="HighIntensity" />
    </mapping>
    <mapping>
      <level value="INFO" />
      <foreColor value="Green" />
    </mapping>
    <mapping>
      <level value="WARN" />
      <foreColor value="Yellow" />
    </mapping>
    <mapping>
      <level value="FATAL" />
      <foreColor value="White" />
      <backColor value="Red" />
    </mapping>

    <layout type="log4net.Layout.PatternLayout">
      <!-- You could change here the date format -->
      <conversionPattern value="%date{yyyy'.'MM'.'dd --- HH':'mm':'ss'.'fff}  [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
    </layout>
  </appender>


  <appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
    <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.2.10.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    <connectionString value="data source=ysg;initial catalog=DBGA_DEV;integrated security=true;persist security info=True;" />
    <commandText value="INSERT INTO [DBGA_DEV].[ga].[tb_Data_Log] ([Date],[Thread],[Level],[Logger],[Message]) VALUES (@log_date, @thread, @log_level, @logger, @message)" />

    <parameter>
      <parameterName value="@log_date" />
      <dbType value="DateTime" />
      <layout type="log4net.Layout.PatternLayout" value="%date{yyyy'.'MM'.'dd HH':'mm':'ss'.'fff}" />
    </parameter>
    <parameter>
      <parameterName value="@thread" />
      <dbType value="String" />
      <size value="255" />
      <layout type="log4net.Layout.PatternLayout" value="%thread" />
    </parameter>
    <parameter>
      <parameterName value="@domainName" />
      <dbType value="String" />
      <size value="255" />
      <layout type="log4net.Layout.PatternLayout" value="%user" />
    </parameter>
    <parameter>
      <parameterName value="@log_level" />
      <dbType value="String" />
      <size value="50" />
      <layout type="log4net.Layout.PatternLayout" value="%level" />
    </parameter>
    <parameter>
      <parameterName value="@logger" />
      <dbType value="String" />
      <size value="255" />
      <layout type="log4net.Layout.PatternLayout" value="%logger" />
    </parameter>
    <parameter>
      <parameterName value="@message" />
      <dbType value="String" />
      <size value="4000" />
      <layout type="log4net.Layout.PatternLayout" value="%message" />
    </parameter>
  </appender>
  <root>
    <level value="ALL" />
    <appender-ref ref="LogFileAppender" />
    <appender-ref ref="AdoNetAppender" />
    <appender-ref ref="ColoredConsoleAppender" />
  </root>
</log4net>
</configuration>
   */
  #region TheReferencesInThecsprojFile
  //<Reference Include="log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821, processorArchitecture=MSIL">
  //  <SpecificVersion>False</SpecificVersion>
  //  <HintPath>..\..\..\Log4Net\log4net-1.2.10\bin\net\2.0\release\log4net.dll</HintPath>
  //</Reference>
  //<Reference Include="nunit.framework, Version=2.4.8.0, Culture=neutral, PublicKeyToken=96d09a1eb7f44a77, processorArchitecture=MSIL" />
  #endregion TheReferencesInThecsprojFile


namespace GenApp.Bo
{
  public class User
  {

    public int LogLevel { get; set; }
    public UserSettings UserSettings { get; set; }


  } //eof class 

  public class UserSettings
  {
    public int LogLevel;
  }

} //eof namespace 

namespace GenApp.Utils
{
  ///<version> 1.1 </version>
  ///<author> Yordan Georgiev </author>
  ///<summary> Wrapper around log4net with dynamically adjustable verbosity</summary>
  public class Logger
  {

    private static Logger inst = new Logger ();
    public static Logger Inst ()
    {
      inst.ConfigureLogging ();
      return inst;
    }


    public enum DebugLevel : int
    {
      Fatal_Msgs = 0,
      Fatal_Error_Msgs = 1,
      Fatal_Error_Warn_Msgs = 2,
      Fatal_Error_Warn_Info_Msgs = 3,
      Fatal_Error_Warn_Info_Debug_Msgs = 4
    }

    public static void Debug ( GenApp.Bo.User userObj, ILog logger, string msg )
    {
      DebugLevel debugLevel = (DebugLevel)userObj.UserSettings.LogLevel;
      string strLogLevel = Logger.GetLogTypeString ( debugLevel );
      inst.SetLogingLevel ( strLogLevel );
      logger.Debug ( msg );

    } //eof method 


    public static void Info ( GenApp.Bo.User userObj, ILog logger, string msg )
    {
      DebugLevel debugLevel = (DebugLevel)userObj.UserSettings.LogLevel;
      string strLogLevel = Logger.GetLogTypeString ( debugLevel );
      inst.SetLogingLevel ( strLogLevel );
      logger.Info ( msg );

    } //eof method 


    public static void Warn ( GenApp.Bo.User userObj, ILog logger, string msg )
    {
      DebugLevel debugLevel = (DebugLevel)userObj.UserSettings.LogLevel;
      string strLogLevel = Logger.GetLogTypeString ( debugLevel );
      inst.SetLogingLevel ( strLogLevel );
      logger.Warn ( msg );

    } //eof method 


    public static void Error ( GenApp.Bo.User userObj, ILog logger, string msg )
    {
      DebugLevel debugLevel = (DebugLevel)userObj.UserSettings.LogLevel;
      string strLogLevel = Logger.GetLogTypeString ( debugLevel );
      inst.SetLogingLevel ( strLogLevel );
      logger.Error ( msg );
    } //eof method 


    public static void Fatal ( GenApp.Bo.User userObj, ILog logger, string msg )
    {
      DebugLevel debugLevel = (DebugLevel)userObj.UserSettings.LogLevel;
      string strLogLevel = Logger.GetLogTypeString ( debugLevel );
      inst.SetLogingLevel ( strLogLevel );
      logger.Fatal ( msg );
    } //eof method 


    /// <summary>
    /// Activates debug level 
    /// </summary>
    /// <sourceurl>http://geekswithblogs.net/rakker/archive/2007/08/22/114900.aspx</sourceurl>
    private void SetLogingLevel ( string strLogLevel )
    {

      this.ConfigureLogging ();
      string strChecker = "WARN_INFO_DEBUG_ERROR_FATAL";

      if (String.IsNullOrEmpty ( strLogLevel ) == true || strChecker.Contains ( strLogLevel ) == false)
        throw new ArgumentOutOfRangeException ( " The strLogLevel should be set to WARN , INFO , DEBUG ," );



      log4net.Repository.ILoggerRepository[] repositories = log4net.LogManager.GetAllRepositories ();

      //Configure all loggers to be at the debug level.
      foreach (log4net.Repository.ILoggerRepository repository in repositories)
      {
        repository.Threshold = repository.LevelMap[strLogLevel];
        log4net.Repository.Hierarchy.Hierarchy hier = (log4net.Repository.Hierarchy.Hierarchy)repository;
        log4net.Core.ILogger[] loggers = hier.GetCurrentLoggers ();
        foreach (log4net.Core.ILogger logger in loggers)
        {
          ( (log4net.Repository.Hierarchy.Logger)logger ).Level = hier.LevelMap[strLogLevel];
        }
      }

      //Configure the root logger.
      log4net.Repository.Hierarchy.Hierarchy h = (log4net.Repository.Hierarchy.Hierarchy)log4net.LogManager.GetRepository ();
      log4net.Repository.Hierarchy.Logger rootLogger = h.Root;
      rootLogger.Level = h.LevelMap[strLogLevel];
    }

    ///<summary>
    ///0 -- prints only FATAL messages 
    ///1 -- prints FATAL and ERROR messages 
    ///2 -- prints FATAL , ERROR and WARN messages 
    ///3 -- prints FATAL  , ERROR , WARN and INFO messages 
    ///4 -- prints FATAL  , ERROR , WARN , INFO and DEBUG messages 
    ///</summary>
    private static string GetLogTypeString ( DebugLevel debugLevel )
    {

      string srtLogLevel = String.Empty;
      switch (debugLevel)
      {
        case DebugLevel.Fatal_Msgs:
          srtLogLevel = "FATAL";
          break;
        case DebugLevel.Fatal_Error_Msgs:
          srtLogLevel = "ERROR";
          break;
        case DebugLevel.Fatal_Error_Warn_Msgs:
          srtLogLevel = "WARN";
          break;
        case DebugLevel.Fatal_Error_Warn_Info_Msgs:
          srtLogLevel = "INFO";
          break;
        case DebugLevel.Fatal_Error_Warn_Info_Debug_Msgs:
          srtLogLevel = "DEBUG";
          break;
        default:
          srtLogLevel = "FATAL";
          break;
      } //eof switch
      return srtLogLevel;

    } //eof GetLogTypeString


    /// <summary>
    /// The path where the configuration is read from.
    /// This value is set upon a call to ConfigureLogging().
    /// </summary>
    private string configurationFilePath;
    public void ConfigureLogging ()
    {
      lock (this)
      {
        bool configured = false;


        #region ConfigureByThePathOfTheEntryAssembly
        // Tells the logging system the correct path.
        Assembly a = Assembly.GetEntryAssembly ();

        if (a != null && a.Location != null)
        {
          string path = a.Location + ".config";

          if (File.Exists ( path ))
          {
            log4net.Config.DOMConfigurator.Configure (
              new FileInfo ( path ) );
            configurationFilePath = path;
            configured = true;
          }
          else
          {
            path = FindConfigInPath ( Path.GetDirectoryName ( a.Location ) );
            if (File.Exists ( path ))
            {
              log4net.Config.DOMConfigurator.Configure (
                new FileInfo ( path ) );
              configurationFilePath = path;
              configured = true;
            }
          }
        }
        #endregion ConfigureByThePathOfTheEntryAssembly


        #region ConfigureByWeb.config
        //// Also, try web.config.
        //if (!configured)
        //{
        //  if (HttpContext.Current != null &&
        //    HttpContext.Current.Server != null &&
        //    HttpContext.Current.Request != null)
        //  {
        //    string path = HttpContext.Current.Server.MapPath (
        //      HttpContext.Current.Request.ApplicationPath );

        //    path = path.TrimEnd ( '\\' ) + "\\Web.config";

        //    if (File.Exists ( path ))
        //    {
        //      log4net.Config.DOMConfigurator.Configure (
        //        new FileInfo ( path ) );
        //      configurationFilePath = path;
        //      configured = true;
        //    }
        //  }
        //}
        #endregion ConfigureByWeb.config


        #region ConfigureByThePathOfTheExecutingAssembly
        if (!configured)
        {
          // Tells the logging system the correct path.
          a = Assembly.GetExecutingAssembly ();

          if (a != null && a.Location != null)
          {
            string path = a.Location + ".config";

            if (File.Exists ( path ))
            {
              log4net.Config.DOMConfigurator.Configure (
                new FileInfo ( path ) );
              configurationFilePath = path;
              configured = true;
            }
            else
            {
              path = FindConfigInPath ( Path.GetDirectoryName ( a.Location ) );
              if (File.Exists ( path ))
              {
                log4net.Config.DOMConfigurator.Configure (
                  new FileInfo ( path ) );
                configurationFilePath = path;
                configured = true;
              }
            }
          }
        }
        #endregion ConfigureByThePathOfTheExecutingAssembly


        #region ConfigureByThePathOfTheCallingAssembly
        if (!configured)
        {
          // Tells the logging system the correct path.
          a = Assembly.GetCallingAssembly ();

          if (a != null && a.Location != null)
          {
            string path = a.Location + ".config";

            if (File.Exists ( path ))
            {
              log4net.Config.DOMConfigurator.Configure (
                new FileInfo ( path ) );
              configurationFilePath = path;
              configured = true;
            }
            else
            {
              path = FindConfigInPath ( Path.GetDirectoryName ( a.Location ) );
              if (File.Exists ( path ))
              {
                log4net.Config.DOMConfigurator.Configure (
                  new FileInfo ( path ) );
                configurationFilePath = path;
                configured = true;
              }
            }
          }
        }
        #endregion ConfigureByThePathOfTheCallingAssembly


        #region ConfigureByThePathOfTheLibIsStored
        if (!configured)
        {
          // Look in the path where this library is stored.
          a = Assembly.GetAssembly ( typeof ( Logger ) );

          if (a != null && a.Location != null)
          {
            string path = FindConfigInPath ( Path.GetDirectoryName ( a.Location ) );
            if (File.Exists ( path ))
            {
              log4net.Config.DOMConfigurator.Configure (
                new FileInfo ( path ) );
              configurationFilePath = path;
              configured = true;
            }
          }
        }
        #endregion ConfigureByThePathOfTheLibIsStored



      } //eof lock   
    } //eof method 



    /// <summary>
    /// Searches for a configuration file in the given path.
    /// </summary>
    private string FindConfigInPath (
      string path )
    {
      string[] files = Directory.GetFiles ( path );

      if (files != null && files.Length > 0)
      {
        foreach (string file in files)
        {
          if (Path.GetExtension ( file ).Trim ( '.' ).ToLower (
            CultureInfo.CurrentCulture ) == "config")
          {
            return file;
          }
        }
      }

      // Not found.
      return string.Empty;
    } //eof method 



    /// <summary>
    /// Remove dynamically appenders
    /// </summary>
    /// <param name="appenderName"></param>
    /// <param name="threshold"></param>
    public static void SetThreshold ( string appenderName, Level threshold )
    {
      foreach (AppenderSkeleton appender in LogManager.GetRepository ().GetAppenders ())
      {
        if (appender.Name == appenderName)
        {
          appender.Threshold = threshold;
          appender.ActivateOptions ();

          break;
        }
      }
    } //eof method 



  } //eof class 


} //eof namespace 

USE [DBGA_DEV]
GO

/****** Object:  Table [ga].[tb_Data_Log]    Script Date: 05/20/2009 12:16:01 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [ga].[tb_Data_Log](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [Date] [datetime] NOT NULL,
    [Thread] [varchar](255) NOT NULL,
    [Level] [varchar](20) NOT NULL,
    [Logger] [varchar](255) NOT NULL,
    [Message] [varchar](4000) NOT NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING ON
GO