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

  <log4net debug="true">


    <appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <File value="logs\"/>
      <AppendToFile value="true" />
      <rollingStyle value="Composite" />
      <MaxSizeRollBackups value="99" />
      <MaximumFileSize value="9000KB" />
      <StaticLogFileName value="false" />
      <DatePattern value="‘‘yyyy-MM-dd‘.log‘" />
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%-5p %d %5rms [%t] %-8.22c{1} %-2.18M - %m%n" />
        <param name="Footer" value="&#13;&#10;" />
      </layout>
    </appender>
    
    <root>
      <level value="All" />
      <appender-ref ref="RollingFile"/>
    </root>    
    
  </log4net>
  
  
</configuration>

string logCfg = Path.Combine(Application.StartupPath, "log4net2.config");
                XmlConfigurator.Configure(new FileInfo(logCfg));

log4net.ILog log = log4net.LogManager.GetLogger("testApp.Logging");//获取一个日志记录器

                log.Info(DateTime.Now.ToString() + ": login success");//写入一条新log