public class Log4netHelper
    {
        static Log4netHelper() 
        {
            string log4netConfigSource = System.Configuration.ConfigurationManager.AppSettings["log4netconfig"];
            string filename = "";
            if (!string.IsNullOrEmpty(log4netConfigSource))
            {
                filename = HttpRuntime.AppDomainAppPath + log4netConfigSource;
                log4net.Config.XmlConfigurator.ConfigureAndWatch(new System.IO.FileInfo(filename));
            }
            else
            {
                throw new Exception("应用系统日志配置文件配置错误！");
            }
        }


        /// <summary>  
        /// 输出日志到Log4Net  
        /// </summary>  
        /// <param name="t"></param>  
        /// <param name="ex"></param>  
        public static void WriteErrorLog(Type t, Exception ex)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Error("Error", ex);
        }



        /// <summary>  
        /// 输出日志到Log4Net  
        /// </summary>  
        /// <param name="t"></param>  
        /// <param name="msg"></param>  
        public static void WriteInfoLog(Type t, string msg)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Info(msg);
        }

    }

<?xml version="1.0" encoding="utf-8" ?>

<log4net>
  <!--定义输出到文件中-->
  <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
    <!--定义文件存放位置-->
    <param name="File" value="Logs\" />
    <param name="AppendToFile" value="true" />
    <param name="RollingStyle" value="Date" />
    <param name="DatePattern" value="yyyy-MM-dd.'log'"  />
    <param name="StaticLogFileName" value="false" />
    <layout type="log4net.Layout.PatternLayout">
      <!--每条日志末尾的文字说明-->
      <!--<footer value="此条记录结束" />-->
      <!--输出格式-->
      <!--样例：2008-03-26 13:42:32,111 [10] INFO  Log4NetDemo.MainClass [(null)] - info-->
      <param name="ConversionPattern" value="%newline记录时间：[%date] 线程ID:[%thread] 日志级别：[%-5level] 出错类：【%logger property:(%property{NDC})] 错误描述：[%message]%newline" />
    </layout>
  </appender>
  <!--定义输出到控制台命令行中-->
  <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
    </layout>
  </appender>
  <!--定义输出到windows事件中-->
  <appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
    </layout>
  </appender>
  <!--定义输出到数据库中，这里举例输出到Access数据库中，数据库为C盘的log4net.mdb-->
  <appender name="AdoNetAppender_Access" type="log4net.Appender.AdoNetAppender">
    <connectionString value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:log4net.mdb" />
    <commandText value="INSERT INTO LogDetails ([LogDate],[Thread],[Level],[Logger],[Message]) VALUES (@logDate, @thread, @logLevel, @logger,@message)" />
    <!--定义各个参数-->
    <parameter>
      <parameterName value="@logDate" />
      <dbType value="String" />
      <size value="240" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@thread" />
      <dbType value="String" />
      <size value="240" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%thread" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@logLevel" />
      <dbType value="String" />
      <size value="240" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%level" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@logger" />
      <dbType value="String" />
      <size value="240" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%logger" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@message" />
      <dbType value="String" />
      <size value="240" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%message" />
      </layout>
    </parameter>
  </appender>
  <!--定义日志的输出媒介，下面定义日志以四种方式输出。也可以下面的按照一种类型或其他类型输出。-->
  <root>
    <!--文件形式记录日志-->
    <appender-ref ref="RollingLogFileAppender" />
    <!--控制台控制显示日志-->
    <!--<appender-ref ref="ConsoleAppender" /> -->
    <!--Windows事件日志-->
    <!--<appender-ref ref="EventLogAppender" />-->
    <!-- 如果不启用相应的日志记录，可以通过这种方式注释掉
      <appender-ref ref="AdoNetAppender_Access" />
      -->
  </root>

</log4net>