（一）使用log4net生成日志文件

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

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <log4net>
    <!-- 信息日志类 -->
    <logger name="loginfo">
      <level value="ALL" />
      <appender-ref ref="InfoAppender" />
    </logger>
    
    <!-- 信息日志附加介质 -->
    <appender name="InfoAppender" type="log4net.Appender.RollingFileAppender">
      <!-- 输出到什么目录 -->
      <param name="File" value="Log\\LogInfo\\" />
      <!-- 是否覆写到文件中 -->
      <param name="AppendToFile" value="true" />
      <!-- 备份文件的个数 -->
      <param name="MaxSizeRollBackups" value="50" />
      <!-- 单个日志文件最大的大小 -->
      <param name="MaxFileSize" value="10240" />
      <!-- 是否使用静态文件名 -->
      <param name="StaticLogFileName" value="false" />
      <!-- 日志文件名 -->
      <param name="DatePattern" value="yyyyMMdd&quot;.htm&quot;" />
      <param name="RollingStyle" value="Date" />
      <!-- 布局，更多参数可参照官网说明 -->
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="&lt;HR COLOR=red&gt;
          %n级别：%-5p &lt;BR&gt;
          %n时间：%d [%t] &lt;BR&gt;
          %n描述：%m &lt;BR&gt;"/>
      </layout>
    </appender>
  </log4net>
</configuration>

[assembly: log4net.Config.XmlConfigurator(ConfigFile = "log4net.config", ConfigFileExtension = "config", Watch = true)]

namespace July.Demo.Win
{
    public class LogHelper
    {
        static readonly log4net.ILog loginfo = log4net.LogManager.GetLogger("loginfo");

        public static void WriteLog(string info)
        {
            if (loginfo.IsInfoEnabled)
            {
                loginfo.Info(info);
            }
        }
    }
}

private void Form1_Load(object sender, EventArgs e)
{
    LogHelper.WriteLog("窗体生成");
}