相关资料：
http://www.cnblogs.com/dragon/archive/2005/03/24/124254.html
注意：
//如果为了使得应用程序的配置文件（web/app.config）不至于很臃肿，把log4net的配置单独放置在
//Log4net.config文件中，那么需要应用程序的AssemblyInfo.cs添加这行代码。目的是程序启动时是找到Log4net.config配置文件。
Lo4net配置文件：
<?xml version="1.0" encoding="utf-8" ?>
<!--
.NET application configuration file
This file must have the exact same name as your application with .config appended to it.For example if your application is ConsoleApp.exe then the config file must be ConsoleApp.exe.config.
It must also be in the same directory as the application.
-->
<configuration>
<!-- Register a section handler for the log4net section -->
<configSections>
<section name="log4net" type="System.Configuration.IgnoreSectionHandler" />
</configSections>
<appSettings>
<!-- To enable internal log4net logging specify the following appSettings key -->
<!-- <add key="log4net.Internal.Debug" value="true"/> -->
</appSettings>
<!-- This section contains the log4net configuration settings -->
<log4net>
<!-- Define some output appenders -->
<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="rolling-log.txt" />
<appendToFile value="true" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="100" />
<rollingStyle value="Size" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<header value="[Header] " />
<footer value="[Footer] " />
<conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
</layout>
</appender>
<appender name="LogFileAppender" type="log4net.Appender.FileAppender">
<file value="log-file.txt" />
<!-- Example using environment variables in params -->
<!-- <file value="${TMP}\log-file.txt" /> -->
<sppendToFile value="true" />
<!-- An alternate output encoding can be specified -->
<!-- <encoding value="unicodeFFFE" /> -->
<layout type="log4net.Layout.PatternLayout">
<geader value="[Header] " />
<footer value="[Footer] " />
<conversionPattern value="%date [%thread] %-5level %logger [%ndc] <%property{auth}> - %message%newline" />
</layout>
<!-- Alternate layout using XML
<layout type="log4net.Layout.XMLLayout" /> -->
</appender>
<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%ndc] <%property{auth}> - %message%newline" />
</layout>
</appender>
<appender name="NetSendAppender" type="log4net.Appender.NetSendAppender">
<threshold value="ERROR" />
<server value="SQUARE" />
<recipient value="nicko" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
</layout>
</appender>
<!-- Example of how to configure the AdoNetAppender
<appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender" >
<connectionString value="Driver={Microsoft Access Driver (*.mdb)};DBQ=C:\Work\cvs_root\log4net-1.2\access.mdb;UID=;PWD=;" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message]) VALUES (‘%date‘,‘%thread‘,‘%level‘,‘%logger‘,‘%message‘)" />
</layout>
</appender>
-->
<!--
<appender name="A" type="log4net.Appender.ForwardingAppender" >
<threshold value="WARN"/>
<appender-ref ref="ConsoleAppender" />
</appender>
<appender name="B" type="log4net.Appender.ForwardingAppender" >
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="DEBUG"/>
<levelMax value="INFO"/>
</filter>
<appender-ref ref="ConsoleAppender" />
</appender>
-->
<!-- Example of how to configure the AdoNetAppender to connect to MS Access -->
<appender name="ADONetAppender_Access" type="log4net.Appender.AdoNetAppender">
<connectionString value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Work\cvs_root\log4net-1.2\access.mdb;User Id=;Password=;" />
<commandText" value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message]) VALUES (@log_date, @thread, @log_level, @logger, @message)" />
<parameter>
<parameterName value="@log_date" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date" />
</param>
</parameter>
<parameter>
<parameterName value="@thread" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%thread" />
</layout>
</parameter>
<parameter>
<parameterName value="@log_level" />
<dbType value="String" />
<size value="50" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level" />
</layout>
</parameter>
<parameter>
<parameterName value="@logger" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%logger" />
</layout>
</parameter>
<parameter>
<parameterName value="@message" />
<dbType value="String" />
<size value="1024" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%message" />
</layout>
</parameter>
</appender>
<!-- Example of how to configure the AdoNetAppender to connect to MS SQL Server -->
<appender name="ADONetAppender_SqlServer" type="log4net.Appender.AdoNetAppender">
<bufferSize value="1" />
<connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<connectionString value="data source=SQLSVR;initial catalog=test_log4net;integrated security=false;persist security info=True;User ID=sa;Password=sa" />
<commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message]) VALUES (@log_date, @thread, @log_level, @logger, @message)" />
<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="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%thread" />
</layout>
</parameter>
<parameter>
<parameterName value="@log_level" />
<dbType value="String" />
<size value="50" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level" />
</layout>
</parameter>
<parameter>
<parameterName value="@logger" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%logger" />
</layout>
</parameter>
<parameter>
<parameterName value="@message" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%message" />
</layout>
</parameter>
</appender>
<!-- Setup the root category, add the appenders and set the default level -->
<root>
<level value="WARN" />
<appender-ref ref="LogFileAppender" />
<appender-ref ref="ConsoleAppender" />
<!-- <appender-ref ref="ADONetAppender_SqlServer" /> -->
<appender-ref ref="NetSendAppender" />
<!-- <appender-ref ref="A" /> -->
</root>
<!-- Specify the level for some specific categories -->
<logger name="ConsoleApp.LoggingExample">
<!-- <appender-ref ref="B" /> -->
<level value="ALL" />
<appender-ref ref="RollingLogFileAppender" />
</logger>
</log4net>
</configuration>