最后别忘了Application_Start()  log4net.Config.XmlConfigurator.Configure();

private static readonly log4net.ILog log =            log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().ReflectedType);

Log4net的安装

Install-Package log4net

1.先弄个日志记录的类

/// 
    /// 使用LOG4NET记录日志的功能，在WEB.CONFIG里要配置相应的节点    /// 
    public class LogHelper    {        //log4net日志专用        public static readonly log4net.ILog loginfo = log4net.LogManager.GetLogger("loginfo");        public static readonly log4net.ILog logerror = log4net.LogManager.GetLogger("logerror");                  public static void SetConfig()        {            log4net.Config.XmlConfigurator.Configure();        }        public static void SetConfig(FileInfo configFile)        {            log4net.Config.XmlConfigurator.Configure(configFile);        }        /// 
        /// 普通的文件记录日志        /// 
        ///         public static void WriteLog(string info)        {            if (loginfo.IsInfoEnabled)            {                loginfo.Info(info);            }        }        /// 
        /// 错误日志        /// 
        ///         ///         public static void WriteLog(string info, Exception se)        {            if (logerror.IsErrorEnabled)            {                logerror.Error(info, se);            }        }  }

在 configSections 节点上添加：

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

 然后配置单独的节点：

3.在GOLBAL文件里调用写日志：

void Application_Start(object sender, EventArgs e)     {        //在应用程序启动时运行的代码                //初始日志的配置        LogHelper.SetConfig();            } void Application_Error(object sender, EventArgs e)     {         //在出现未处理的错误时运行的代码        Exception objExp = HttpContext.Current.Server.GetLastError();        string username = "";        string userid = "";        if (Session["ulogin"] != null)        {             string[] uinfo=Session["ulogin"].ToString().Split('|');            userid = uinfo[0];            username = uinfo[1];        }        Aotain114.Public.LogHelper.WriteLog("\r\n用户ID:"+userid+"\r\n用户名:"+username+"\r\n客户机IP:" + Request.UserHostAddress + "\r\n错误地址:" + Request.Url + "\r\n异常信息:" + Server.GetLastError().Message, objExp);            }