写在前面

Log4Net是从Java的log4j移植过来的，功能也与log4j类似，可以把日志信息输出到文件、数据库、控制台、Windows 事件日志、远程系统日志服务等不同的介质或目标。

Log4Net配置选项丰富灵活，并且可在运行时动态更新配置并应用，允许同时推送到多个目标；虽然项目已经休眠了，但是该类库已久经考验，经典的设计永不过时。

获取类库

可通过NuGet获取类库，引入到项目中。

配置模板

新建log4net.xml文件，命名成log4net.config也可以，初始化时保持一致即可，配置内容如下：

<?xml version="1.0" encoding="utf-8"?>
<log4net>
  <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger %ndc - %message%newline" />
    </layout>
  </appender>
  <appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender" LEVEL="INFO">
    <!--防止多线程时不能写Log,官方说线程非安全-->
    <param name="LockingModel" type="log4net.Appender.FileAppender+MinimalLock" />
    <param name="File" value="Logs/" />
    <param name="AppendToFile" value="true"/>
    <param name="StaticLogFileName" value="false" />
    <param name="DatePattern" value="yyyy-MM-dd.'info.log'" />
    <param name="RollingStyle" value="Date"/>
    <param name="MaxSizeRollBackups" value="10" />
    <param name="MaximumFileSize" value="5MB" />
    <layout type="log4net.Layout.PatternLayout">
      <param name="ConversionPattern" value="## %d [%t] %-5p %x %m %n"/>
      <!--<param name="ConversionPattern" value="%date [%thread] %-5level [%logger] %ndc - %message%newline" />-->
    </layout>
    <filter type="log4net.Filter.LevelRangeFilter">
      <param name="LevelMin" value="INFO" />
      <param name="LevelMax" value="INFO" />
    </filter>
  </appender>
  <appender name="ErrorFileAppender" type="log4net.Appender.RollingFileAppender" LEVEL="ERROR">
    <param name="LockingModel" type="log4net.Appender.FileAppender+MinimalLock" />
    <param name="File" value="Logs/" />
    <param name="AppendToFile" value="true"/>
    <param name="StaticLogFileName" value="false" />
    <param name="DatePattern" value="yyyy-MM-dd.'error.log'" />
    <param name="RollingStyle" value="Date"/>
    <param name="MaxSizeRollBackups" value="10" />
    <param name="MaximumFileSize" value="5MB" />
    <layout type="log4net.Layout.PatternLayout">
      <param name="ConversionPattern" value="%date [%thread] %-5level [%logger] %ndc - %message%newline" />
    </layout>
    <filter type="log4net.Filter.LevelRangeFilter">
      <param name="LevelMin" value="WARN" />
      <param name="LevelMax" value="ERROR" />
    </filter>
  </appender>
  <appender name="DebugFileAppender" type="log4net.Appender.RollingFileAppender" LEVEL="ERROR">
    <param name="LockingModel" type="log4net.Appender.FileAppender+MinimalLock" />
    <param name="File" value="Logs/" />
    <param name="AppendToFile" value="true"/>
    <param name="StaticLogFileName" value="false" />
    <param name="DatePattern" value="yyyy-MM-dd.'debug.log'" />
    <param name="RollingStyle" value="Date"/>
    <param name="MaxSizeRollBackups" value="10" />
    <param name="MaximumFileSize" value="5MB" />
    <layout type="log4net.Layout.PatternLayout">
      <param name="ConversionPattern" value="%date [%thread] %-5level [%logger] %ndc - %message%newline" />
    </layout>
    <filter type="log4net.Filter.LevelRangeFilter">
      <param name="LevelMin" value="DEBUG" />
      <param name="LevelMax" value="DEBUG" />
    </filter>
  </appender>
  <root>
    <level value="All" />
    <appender-ref ref="LogFileAppender" />
    <appender-ref ref="ErrorFileAppender"/>
    <appender-ref ref="DebugFileAppender" />
    <appender-ref ref="ConsoleAppender" />
  </root>
</log4net>

 将文件属性中的“复制到输出目录”配置为始终复制，这样配置文件会同步置执行或发布目录。

 引用并初始化类库

      
static Program()
{
    //加载log4net配置
    log4net.Config.XmlConfigurator.ConfigureAndWatch(new FileInfo(AppDomain.CurrentDomain.BaseDirectory + @"\log4net.xml"));
}

也可以在AssemblyInfo.cs中进行初始化配置

[assembly: log4net.Config.XmlConfigurator(ConfigFile = "log4Net.xml")] 

 工具类

    public static class LogHelper
    {
        public static void Info(object msg, params object[] parameters)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Info(msg);
        }

        public static void Debug(string msg)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Debug(msg);
        }

        public static void Error(string msg)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Error(msg);
        }

        public static void FormatError(string format, params object[] args)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Error(string.Format(format, args));
        }

        public static void Error(Exception ex)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Error(ex.Message, ex);
        }

        public static void Error(object msg, Exception ex)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Error(msg, ex);
        }

        public static void Warn(object msg, Exception ex)
        {
            var log = LogManager.GetLogger("log4netlogger");
            log.Warn(msg, ex);
        }

        public static void Log(string msg)
        {
            Info(msg);
        }

        public static void Log(Exception ex)
        {
            Error(ex);
        }

    }

调用示例

LogHelper.Info("事件类型出错，类型：" + _rv.EventType + "，参数：" + _rv.EventArgs);

LogHelper.Debug(string.Format("action_finish：{0}", TacticsName));

LogHelper.Error(string.Format("json序列化失败：{0}", json), ex);