log4net 全局配置

 public class LogHelper
    {
      private static readonly log4net.ILog ILogInfo = log4net.LogManager.GetLogger("loginfo");

      public static readonly log4net.ILog ILogError = log4net.LogManager.GetLogger("logerror");

        public static void Info(string msg)
        {
            ILogInfo.Info(msg);
        }

        public static void FileNameInfo(string filename, string msg)
        {
            ILogInfo.Info(filename + " " + msg);
        }

        public static void Error(string msg)
        {
            ILogError.Error(msg);
        }

        public static void FileNameError(string filename, string msg)
        {
            ILogError.Error(filename + " " + msg);
        }
    }

Web.config里面

 <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />

  <log4net>
    <logger name="logerror">
      <level value="ERROR" />
      <appender-ref ref="ErrorAppender" />
    </logger>
    <logger name="loginfo">
      <level value="INFO" />
      <appender-ref ref="InfoAppender" />
    </logger>
    <appender name="ErrorAppender" type="log4net.Appender.RollingFileAppender">
      <param name="File" value="Log\Error\" />
      <param name="AppendToFile" value="true" />
      <param name="CountDirection" value="-1" />
      <param name="MaxSizeRollBackups" value="" />
      <param name="MaximumFileSize" value="5MB" />
      <param name="lockingModel" type="log4net.Appender.FileAppender+MinimalLock" />
      <rollingStyle value="Date" />
      <datePattern value="yyyyMMdd'.txt'" />
      <staticLogFileName value="false" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%d [%t]%c %m%n" />
      </layout>
    </appender>
    <appender name="InfoAppender" type="log4net.Appender.RollingFileAppender">
      <param name="File" value="Log\Info\" />
      <param name="AppendToFile" value="true" />
      <param name="CountDirection" value="-1" />
      <param name="MaxSizeRollBackups" value="" />
      <param name="MaximumFileSize" value="5MB" />
      <param name="lockingModel" type="log4net.Appender.FileAppender+MinimalLock" />
      <rollingStyle value="Date" />
      <datePattern value="yyyyMMdd'.txt'" />
      <staticLogFileName value="false" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%d [%t]%c %m%n" />
      </layout>
    </appender>
  </log4net>

Global.asax里面：

  log4net.Config.XmlConfigurator.Configure();