log4net

1.引用log4net.dll文件

2.添加配置文件

<?xml version="1.0"?>
<configuration>
  <configSections>
    <!--log4net配置安装-->
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net"/>
  </configSections>
  <log4net>
    <!--记录器root可以被其他继承-->
    <root>
      <level value="ALL" />
      <appender-ref ref="ConsoleAppender" />
      <appender-ref ref="FileAppender" />
    </root>
    <!--记录器OtherClass这个类才有的日志级别-->
    <logger name="log4netSample.OtherClass">
      <level value="DEBUG"/>
      <appender-ref ref="ConsoleAppender"/>
      <appender-ref ref="FileAppender" />
    </logger>
    <!--输出到控制台-->
    <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender,log4net">
      <layout type="log4net.Layout.PatternLayout,log4net">
        <param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n" />
      </layout>
    </appender>

    <!--<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date{ABSOLUTE} 
    [%thread] %level %logger - %message%newline"/>
      </layout>
      <filter type="log4net.Filter.StringMatchFilter">
        <stringToMatch value="test" />
      </filter>
      <filter type="log4net.Filter.DenyAllFilter" />
    </appender>-->

    <!--保存到文件-->
    <appender name="FileAppender" type="log4net.Appender.FileAppender">
      <file value="mylogfile.txt" />
      <appendToFile value="true" />
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
      </layout>
      <filter type="log4net.Filter.LevelRangeFilter">
        <levelMin value="INFO" />
        <levelMax value="FATAL" />
      </filter>
    </appender>
  </log4net>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
</configuration>

 注意，如果配置文件里面还有其他内容，比如数据库连接串之类的，都要放在log4net之后，否则会出错

3.读取配置信息

也可以在每次调用的地方

 log4net.Config.XmlConfigurator.Configure();

4.调用

namespace log4netSample
{
   public class OtherClass
    {
       public static void Log4NetSayHello() {
           log4net.Config.XmlConfigurator.Configure();
           log4net.ILog logger = log4net.LogManager.GetLogger(typeof(OtherClass));
           logger.Error("这也是一个日志消息");
       }
    }
}

namespace log4netSample
{
    class Program
    {
        static void Main(string[] args)
        {
            log4net.ILog logger = log4net.LogManager.GetLogger(typeof(Program));
            logger.Debug("这是一个日志消息");

            OtherClass.Log4NetSayHello();
            Console.ReadKey();
        }
    }
}