使用log4net-1.2.0-beta8
在项目的AssemblyInfo.cs文件中设置

[assembly: log4net.Config.DOMConfiguratorAttribute(Watch=true)]
添加并编辑项目配置文件（默认为App.config），内容如下：
<?xml version=\"1.0\" encoding=\"utf-8\" ?>
<configuration>
<configSections>
<section name=\"log4net\" type=\"log4net.Config.Log4NetConfigurationSectionHandler, log4net\"/>
</configSections>
<log4net>
<appender name=\"stdout\" type=\"log4net.Appender.ConsoleAppender\" >
<layout type=\"log4net.Layout.PatternLayout\">
<!--conversionPattern value=\"[%d %l] %n%m%n\" /-->
<param name=\"ConversionPattern\" value=\"[%d %l] %m%n\" />
</layout>
</appender>
<appender name=\"file\" type=\"log4net.Appender.FileAppender\">
<param name=\"File\" value=\"log.txt\" />
<param name=\"AppendToFile\" value=\"true\" />
<layout type=\"log4net.Layout.PatternLayout\">
<param name=\"ConversionPattern\" value=\"[%d %l] %m%n\" />
</layout>
</appender>


<root>
<level value=\"ALL\" />
<appender-ref ref=\"stdout\" />
<appender-ref ref=\"file\" />
</root>

<logger name=\"*\">
<level value=\"ALL\" />
<appender-ref ref=\"stdout\" />
<appender-ref ref=\"file\" />
</logger>
</log4net>
</configuration>



程序代码中使用如下语句
...
using log4net;
using log4net.Config;
...
private static ILog log = LogManager.GetLogger(typeof(TestClass));
...
log.Info(\"This is a test!\");

ok!收工