1.引用log4net.dll文件

2.添加配置文件

 1 <?xml version="1.0"?>
 2 <configuration>
 3   <configSections>
 4     <!--log4net配置安装-->
 5     <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net"/>
 6   </configSections>
 7   <log4net>
 8     <!--记录器root可以被其他继承-->
 9     <root>
10       <level value="ALL" />
11       <appender-ref ref="ConsoleAppender" />
12       <appender-ref ref="FileAppender" />
13     </root>
14     <!--记录器OtherClass这个类才有的日志级别-->
15     <logger name="log4netSample.OtherClass">
16       <level value="DEBUG"/>
17       <appender-ref ref="ConsoleAppender"/>
18       <appender-ref ref="FileAppender" />
19     </logger>
20     <!--输出到控制台-->
21     <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender,log4net">
22       <layout type="log4net.Layout.PatternLayout,log4net">
23         <param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n" />
24       </layout>
25     </appender>
26 
27     <!--<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
28       <layout type="log4net.Layout.PatternLayout">
29         <conversionPattern value="%date{ABSOLUTE} 
30     [%thread] %level %logger - %message%newline"/>
31       </layout>
32       <filter type="log4net.Filter.StringMatchFilter">
33         <stringToMatch value="test" />
34       </filter>
35       <filter type="log4net.Filter.DenyAllFilter" />
36     </appender>-->
37 
38     <!--保存到文件-->
39     <appender name="FileAppender" type="log4net.Appender.FileAppender">
40       <file value="mylogfile.txt" />
41       <appendToFile value="true" />
42       <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
43       <layout type="log4net.Layout.PatternLayout">
44         <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
45       </layout>
46       <filter type="log4net.Filter.LevelRangeFilter">
47         <levelMin value="INFO" />
48         <levelMax value="FATAL" />
49       </filter>
50     </appender>
51   </log4net>
52   <startup>
53     <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
54   </startup>
55 </configuration>

 注意，如果配置文件里面还有其他内容，比如数据库连接串之类的，都要放在log4net之后，否则会出错

3.读取配置信息

也可以在每次调用的地方

1  log4net.Config.XmlConfigurator.Configure();

4.调用

 1 namespace log4netSample
 2 {
 3    public class OtherClass
 4     {
 5        public static void Log4NetSayHello() {
 6            log4net.Config.XmlConfigurator.Configure();
 7            log4net.ILog logger = log4net.LogManager.GetLogger(typeof(OtherClass));
 8            logger.Error("这也是一个日志消息");
 9        }
10     }
11 }

 1 namespace log4netSample
 2 {
 3     class PRogram
 4     {
 5         static void Main(string[] args)
 6         {
 7             log4net.ILog logger = log4net.LogManager.GetLogger(typeof(Program));
 8             logger.Debug("这是一个日志消息");
 9 
10             OtherClass.Log4NetSayHello();
11             Console.ReadKey();
12         }
13     }
14 }