.Net魔法堂：log4net详解

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
  <section name="log4net" type="System.Configuration.IgnoreSectionHandler"/>
</configSections>
<log4net>
  <!-- 定义日志的输出媒介 -->
  <root>
    <appender-ref ref="ConsoleAppender"/>
    <appender-ref ref="R"/>
  </root>
  <!-- 定义输出到控制台 -->
  <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
    <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline"/>
    </layout> 
  </appender>
  <!-- 定义输出到日志文件 -->
  <appender name="R" type="log4net.Appender.FileAppender" rollingStyle="Date" datePattern="yyyyMMdd-HH:mm:ss">
    <file value="logs/log.txt"></file>
    <appendToFile value="true"></appendToFile>
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%-d{yyyy-MM-dd HH\:mm\:ss}  [%L] [%c]-[%p] %m%n"></conversionPattern> 
    </layout>
  </appender>
</log4net>
</configuration>

/**
 * 指定log4net使用.config文件来读取配置信息
 * 若为Winform（假定程序为Demo.exe）, 那么配置文件则为Demo.exe.config
 * 若为Webform，则为web.config
 */
[assembly:log4net.Config.XmlConfigurator(Watch=true)]
namespace Demo{
  public class MainClass{
    public static void Main(String[] args){
    ILog log = log4net.LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        log.Error("error", new Exception("there is an exception"));
        log.Fatal("fatal", new Exception("there is a deadly exception occurs"));
    log.Info("info");
    log.Debug("debug");
    log.Warn("warn");
    Console.Read();
    }
  }
}

<appender name="FileAppender" type="log4net.Appender.FileAppender"
 file="logs/log.txt" appendToFile="true">
  <layout type="log4net.Layout.PatternLayout">
    ..........
  </layout>
</appender>

<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender" 
 file="logs/log.txt" appendToFile="true" rollingStyle="Size" maxSizeRollBackups="10" maximumFileSize="100KB" staticLogFileName="true">
  <layout type="log4net.Layout.PatternLayout">
    ..........
  </layout>
</appender>

<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender" 
file="logs/log.txt" appendToFile="true" rollingStyle="Date" datePattern="yyyyMMdd">
  <layout type="log4net.Layout.PatternLayout">
    ..........
  </layout>
</appender>

// 和PatternLayout一起使用FileAppender

log4net.Config.BasicConfigurator.Configure(

  new log4net.Appender.FileAppender(

     new log4net.Layout.PatternLayout("%d

       [%t]%-5p %c [%x] - %m%n"),"testfile.log"));

// using a FileAppender with an XMLLayout

log4net.Config.BasicConfigurator.Configure(

  new log4net.Appender.FileAppender(

    new log4net.Layout.XMLLayout(),"testfile.xml"));

// using a ConsoleAppender with a PatternLayout

log4net.Config.BasicConfigurator.Configure(

  new log4net.Appender.ConsoleAppender(

    new log4net.Layout.PatternLayout("%d [%t] %-5p %c - %m%n")));

// using a ConsoleAppender with a SimpleLayout

log4net.Config.BasicConfigurator.Configure(

  new log4net.Appender.ConsoleAppender(new

    log4net.Layout.SimpleLayout()));

<configSections>
  <section name="log4net" type="System.Configuration.IgnoreSectionHandler"/>
</configSections>

<root>
  <!-- level节点用于定义处理哪个级别的日志事件，缺省值为DEBUG -->
  <level>INFO</level>
  <!-- appender-ref节点用于定义日志对象所使用的Appender对象 -->
  <appender-ref ref="appender节点的name属性值"/>
</root>

<!-- additivity特性设置为false时，日志对象将不继承根日志的appender-ref节点信息。缺省值为true -->
<logger name="test.Logging" additivity="false">
  <!-- 覆盖根日志的level设置 -->
  <level value="WARN"/>
</logger>

log4net.LogManager.GetLogger("test.Logging");

<appender name="appender1" type="log4net.Appender.FileAppender">
  <layout type="log4net.Laytout.PatternLayout">
    <conversionPattern value=".........."/>
  </layout>
  <filter type="log4net.Filter.LevelRangeFilter" levelMin="DEBUG" levelMax="WARN">
  </filter>
</appender>

[assembly:log4net.Config.DOMConfigurator([ConfigFile="配置文件名"|ConfigFileExtension="编译后配置文件的扩展名"][Watch=true/false])

/**
 * 由于触发日志事件时，会检查日志对象的级别是否满足日志事件的级别
 * 先检测日志对象的级别，才触发日志事件 
 */
if (log.IsDebugEnabled) log.Debug("message.....");