这种方法比第一种方法麻烦些

Log4Net.config

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

<configuration>

  <!-- Author:GaoBingBing-->

  <configSections>

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

  </configSections>

  <log4net>

    <!--写入到数据库-->

    <appender name="ADONetAppender_DbServer" type="log4net.Appender.AdoNetAppender">

      <!--错误队列数据达到5个才持久化到数据库-->

      <bufferSize value="" />

      <param name="ConnectionType" value="MySql.Data.MySqlClient.MySqlConnection, MySql.Data"/>

      <param name="ConnectionString" value="Data Source=ip;initial catalog=test;user id=test;password=****;pooling=true;min pool size=1; max pool size=5;Connection Timeout=100;"/>

      <commandText value="INSERT INTO xiao_log(Date,Thread,Level,Logger,Message,UserId,UserName)VALUES(@log_date, @thread, @log_level, @logger, @message,@userid,@username)"/>

      <parameter>

        <parameterName value="@log_date"/>

        <dbType value="DateTime"/>

        <layout type="log4net.Layout.PatternLayout">

          <conversionPattern value="%date{yyyy'-'MM'-'dd HH':'mm':'ss'.'fff}" />

        </layout>

        <!-- <layout type="log4net.Layout.RawTimeStampLayout"/>-->

      </parameter>

      <parameter>

        <parameterName value="@thread"/>

        <dbType value="String"/>

        <size value=""/>

        <layout type="log4net.Layout.PatternLayout">

          <conversionPattern value="%thread"/>

        </layout>

      </parameter>

      <parameter>

        <parameterName value="@log_level"/>

        <dbType value="String"/>

        <size value=""/>

        <layout type="log4net.Layout.PatternLayout">

          <conversionPattern value="%level"/>

        </layout>

      </parameter>

      <parameter>

        <parameterName value="@logger"/>

        <dbType value="String"/>

        <size value=""/>

        <layout type="log4net.Layout.PatternLayout">

          <conversionPattern value="%logger"/>

        </layout>

      </parameter>

      <parameter>

        <parameterName value="@message"/>

        <dbType value="String"/>

        <size value=""/>

        <layout type="log4net.Layout.PatternLayout">

          <conversionPattern value="%message"/>

        </layout>

      </parameter>

      <!--自定义字段-->

      <!--方法二-->

      <parameter>

        <parameterName value="@userid"/>

        <dbType value="String" />

        <size value="" />

        <layout type="Log4Net.MyLayout">[注意了：这里的Log4Net是命名空间 ，MyLayOut是类名]

          <conversionPattern value="%userid" />

        </layout>

      </parameter>

      <parameter>

        <parameterName value="@username"/>

        <dbType value="String" />

        <size value="" />

        <layout type="Log4Net.MyLayout">

          <conversionPattern value="%username" />

        </layout>

      </parameter>

    </appender>

    <root>

      <level value="ALL"/>

      <appender-ref ref="ADONetAppender_DbServer"/>

    </root>

    <!-- Specify the level for some specific categories -->

    <logger name="iNotes">

      <!-- <appender-ref ref="B" /> -->

      <level value="ALL"/>

      <appender-ref ref="ADONetAppender_DbServer"/>

    </logger>

  </log4net>

</configuration>

创建LogMessage.cs,类里面是所有的自定义字段属性

namespace Log4net

{

    public class LogMessage

    {

        public string _userid;

        public string _username;

        public LogMessage() { }

        public LogMessage(string userId, string userName)

        {

            _userid = userId;

            _username = userName;

        }

        public string UserId

        {

            get { return _userid; }

            set { _userid = value; }

        }

        public string UserName

        {

            get { return _username; }

            set { _username = value; }

        }

    }

}

创建  ParemterContent.cs  添加参数转换器类，每个字段一个模式转化类

namespace Log4net

{

    public class ParemterContent

    {

        internal sealed class UserIdParam : PatternLayoutConverter

        {

            // Methods

            protected override void Convert(TextWriter writer, LoggingEvent loggingEvent)

            {

                LogMessage content = loggingEvent.MessageObject as LogMessage;

                if (content != null)

                {

                    writer.Write(content.UserId);

                }

            }

        }

        internal sealed class UserNameParam : PatternLayoutConverter

        {

            protected override void Convert(TextWriter writer, LoggingEvent loggingEvent)

            {

                LogMessage content = loggingEvent.MessageObject as LogMessage;

                if (content != null)

                {

                    writer.Write(content.UserName);

                }

            }

        } 

    }

} 

创建 MyLayout.cs  这个是不是很眼熟 <layout type="Log4Net.MyLayout">

namespace Log4net

{

    internal class MyLayout : PatternLayout

    {

        public MyLayout()

        {

            this.AddConverter("username", typeof(ParemterContent.UserNameParam));

            this.AddConverter("userid", typeof(ParemterContent.UserIdParam));

        }

    }

}

    log4net.ILog loger = log4net.LogManager.GetLogger("iNotes");

                Log4net.LogMessage msg = new LogMessage("", "dajiahao!");

                loger.Info(msg);

如果插入不成功需要检查  Ptoperties下面的AssemblyInfo.cs是不是加入了

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

Global.asax是不是加入了

            LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

如果缺少则需要加上。

如果还不成功 则检查Log4net.config配置文件，肯定xml中自定义属性有问题