log4net

1. 下载 https://logging.apache.org/log4net/download_log4net.cgi，或NuGet搜索“log4net”。
2. 修改配置文件
   

   <?xml version="1.0" encoding="utf-8"?>
   <configuration>
     <configSections>
       <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
     </configSections>
     <log4net>
       <appender name="RollingLogFileAppender_DateFormat" type="log4net.Appender.RollingFileAppender">
         <file value="LogsLog_" />
         <appendToFile value="true" />
         <rollingStyle value="Date" />
         <datePattern value="yyyyMMdd'.txt'" />
         <staticLogFileName value="false"/>
         <layout type="log4net.Layout.PatternLayout">
           <footer value="————————————————————————————————————————————————————————————"/>
           <conversionPattern value="%n【日志级别】%-5level 
   %n【记录时间】%date 
   %n【线程编号】[%thread] 
   %n【执行时间】[%r]毫秒 
   %n【出错文件】%file 
   %n【出错行号】%line 
   %n【错误描述】%message 
   %n【错误详情】" />
         </layout>
       </appender>
       <root>
         <appender-ref ref="RollingLogFileAppender_DateFormat" />
       </root>
     </log4net>
   </configuration>

   注意：configSections 节点，一点要放到 configuration 下第一个。

3. 代码中添加 [assembly: log4net.Config.XmlConfigurator(Watch = true)]，这么一行。我放在AssemblyInfo.cs里了。
4. 代码：
   

   ILog Logger = LogManager.GetLogger("XXX");
   //log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
   try
   {
       
   }
   catch (Exception e)
   {
       Program.Logger.Error("错误描述", e);
   }