log4日志组件在.netcore中的应用

1.安装log4包

 2.新建一个xml格式的配置文件，可以任意名字，例如起名叫log4config.xml

3.添加配置信息，主要是

<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender,log4net">这个节点的内容。
参考地址：
1.RollingFileAppender Class (apache.org)
2.Apache log4net – Apache log4net: Config Examples - Apache log4net

<?xml version="1.0" encoding="utf-8"?>
<configuration>

    <!-- This section contains the log4net configuration settings -->
    <log4net>
        <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
            <layout type="log4net.Layout.PatternLayout" value="%date [%thread] %-5level %logger - %message%newline" />
        </appender>
        <appender name="FileAppender" type="log4net.Appender.FileAppender">
            <file value="./logTom2/log.txt" />
            <appendToFile value="true" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
            </layout>
        </appender>
        <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender,log4net">
            <file value="./LogTom/log2021" />
            <appendToFile value="true" />
            <!--按照何种方式产生多个日志文件(日期[Date],文件大小[Size],混合[Composite])-->
            <rollingStyle value="Composite" />
            <RollingStyle value="Date" />
            <staticLogFileName value="false" />
            <datePattern value="yyyy.MM.dd'.log'" />
            <!--最多产生的日志文件数，超过则只保留最新的n个。设定值value="－1"为不限文件数-->
            <maxSizeRollBackups value="10" />
      <maximumFileSize value="1MB" />
            <layout type="log4net.Layout.PatternLayout,log4net">
                <ConversionPattern value="%d [%t] %-5p %c - %m%n" />
                <Header value="&#xD;&#xA;----------------------Header--------------------------&#xD;&#xA;" />
                <Footer value="&#xD;&#xA;----------------------Footer--------------------------&#xD;&#xA;" />
            </layout>
        </appender>
        <!-- Setup the root category, add the appenders and set the default level -->
        <root>
            <level value="ALL" />
            <appender-ref ref="ConsoleAppender" />
            <!--<appender-ref ref="FileAppender" />-->
            <appender-ref ref="RollingLogFileAppender" />
        </root>
    </log4net>
</configuration>

 4.在startup类中依赖注入log4net

 public static ILoggerRepository LogRepository { get; set; }
    public Startup(IConfiguration configuration)
    {
      Configuration = configuration;
      LogRepository = LogManager.CreateRepository("NETCoreRepository");   //仓库的名字可以在配置文件中配置，也可以直接写死
      XmlConfigurator.Configure(LogRepository, new FileInfo("log4Config.xml"));  //读取配置文件

    }

5.在action中使用

_log.Info(userModel.firstName);
_log.Error(DateTime.Now.ToString() + " error test");