如何在VS2010下使用Log4Net

log4net has a known issue of referencing a System.Web component which is not part of the .NET Framework 4 Client Profile and the VS2010 by default sets project target to be the lightweighted Client Profile. The solution is to change the target to .NET Framework 4:

Right click project -> properties -> Application. Change:

 
.
NET 
Framework

 
4

 
Client

 
Profile

 

to be:

 
.
NET 
Framework

 
4

 

... and that should work, i.e. you can use log4net again...

来自：http://stackoverflow.com/questions/1767253/log4net-with-net-4-0

 范例：

App.config

 

<?
xml
 
version
=
"1.0"
?>
<
configuration
>
  <
configSections
>
    <
section
 
name
=
"log4net"
 
type
="log4net.Config.Log4NetConfigurationSectionHandler,
 log4net-net-1.0" />
  </
configSections
>
  <
log4net
>
    <
root
>
      <
level
 
value
=
"ALL"
 
/>
      <
appender-ref
 
ref
=
"LogFileAppender"
 
/>
    </
root
>
    <
appender
 
name
=
"LogFileAppender"
 
type
=
"log4net.Appender.FileAppender"
 
>
      <
param
 
name
=
"File"
 
value
=
"log-file.txt"
 
/>
      <
param
 
name
=
"AppendToFile"
 
value
=
"true"
 
/>
      <
layout
 
type
=
"log4net.Layout.PatternLayout"
>
        <
param
 
name
=
"ConversionPattern"
 
value
=
"%d [%t] %-5p %c [%x] <%X{auth}>%n - %m%n"
 
/>
      </
layout
>
    </
appender
>
  </
log4net
>
  <
startup
>
    <
supportedRuntime
 
version
=
"v4.0"
 
sku
=
".NETFramework,Version=v4.0"
/>
  </
startup
>
</
configuration
>

注意：configSections节点和startup节点的顺序，否则只见文件而无法输出日志

AssemblyInfo.cs中添加

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

.cs代码正常使用

log4net.ILog log = log4net.LogManager.GetLogger(
"MyLogger"
);
log.Debug("test"
);
原文地址：http://blog.csdn.net/Maths_bai/archive/2010/12/13/6074337.aspx