二、.net6使用Log4Net

--Nuget引入 ：
1. Log4Net 

2. Microsoft.Extensions.Logging.Log4Net.AspNetCore 

--注册：

 builder.Logging.AddLog4Net("CfgFile/log4net.Config");

--Log4Net日志级别

日志级别：控制级别，由低到高：ALL-DEBUG-INFO-WARN-ERROR-FATAL-OFF

--log4net.Config 配置文件

<?xml version="1.0" encoding="utf-8"?>
<log4net>
    <!--指定日记记录方式，以滚动文件的方式（文件记录）-->
    <appender name="rollingAppender" type="log4net.Appender.RollingFileAppender">
        <!--日志路径-->
        <file value="log\log.txt" />
        <!--追加日志内容-->
        <appendToFile value="true" />

        <!--防止多线程时不能写Log,官方说线程非安全-->
        <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />

        <!--可以为:Once|Size|Date|Composite-->
        <!--Composite为Size和Date的组合-->
        <rollingStyle value="Composite" />

        <!--当备份文件时,为文件名加的后缀-->
        <datePattern value="yyyyMMdd.TXT" />

        <!--log保留天数-->
        <maxSizeRollBackups value="20" />

        <!--每个文件最大3M 可用的单位:KB|MB|GB-->
        <maximumFileSize value="3MB" />

        <!--日志文件名是否是固定不变的-->
        <staticLogFileName value="true" />
        <!--日志根据日期滚动-->
        <param name= "RollingStyle" value= "Date"/>

        <!--输出级别在INFO和ERROR之间的日志-->
        <filter type="log4net.Filter.LevelRangeFilter">
            <param name="LevelMin" value="ALL" />
            <param name="LevelMax" value="FATAL" />
        </filter>
        <!--布局-->
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline"/>
        </layout>
    </appender>

    <!--发邮件-->
    <appender name="LogSmtpAppender" type="log4net.Appender.SmtpAppender">
        <authentication value="Basic" />
        <!--接受邮件的邮箱-->
        <to value="7778888@qq.com" />
        <!--发送邮件的邮箱-->
        <from value="123456@126.com" />
        <!--发送邮件的邮箱-->
        <username value="123456@126.com" />
        <!--发送邮件的邮箱密码-->
        <password value="123456" />
        <!--标题-->
        <subject value="XXX应用错误日志消息" />
        <!--smtp.qq.com-->
        <smtpHost value="smtp.126.com" />
        <bufferSize value="2048" />
        <!--超长部分是否丢弃-->
        <lossy value="true" />
        <!--日志级别 大于 WARN 的才发邮件-->
        <evaluator type="log4net.Core.LevelEvaluator">
            <threshold value="ERROR"/>
        </evaluator>
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value=" %level :: %message %newlineLogger: %logger%newline Date: %date%newline" />
        </layout>
    </appender>
    
    <!-- 控制台日志 -->
    <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%n%d{yyyy-MM-dd HH:mm:ss} %m%n" />
        </layout>
        <!--指定范围内的等级才可以被记录-->
        <!--<filter type="log4net.Filter.LevelRangeFilter">
    <param name="LevelMin" value="Info" />
    <param name="LevelMax" value="Fatal" />
   </filter>-->
    </appender >

    <!--数据库日记-->
    <appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
        <bufferSize value="1" />
        <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
        <connectionString value="data source=.;initial catalog=TextDemo;integrated security=false;persist security info=True;User ID=sa;Password=123456" />
        <commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message],[Exception]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception)" />
        <parameter>
            <parameterName value="@log_date" />
            <dbType value="DateTime" />
            <layout type="log4net.Layout.RawTimeStampLayout" />
        </parameter>
        <parameter>
            <parameterName value="@thread" />
            <dbType value="String" />
            <size value="255" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%thread" />
            </layout>
        </parameter>
        <parameter>
            <parameterName value="@log_level" />
            <dbType value="String" />
            <size value="50" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%level" />
            </layout>
        </parameter>
        <parameter>
            <parameterName value="@logger" />
            <dbType value="String" />
            <size value="255" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%logger" />
            </layout>
        </parameter>
        <parameter>
            <parameterName value="@message" />
            <dbType value="String" />
            <size value="4000" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%message" />
            </layout>
        </parameter>
        <parameter>
            <parameterName value="@exception" />
            <dbType value="String" />
            <size value="2000" />
            <layout type="log4net.Layout.ExceptionLayout" />
        </parameter>
    </appender>

    <root>
        <priority value="ALL"/>
        <!--(高) OFF > FATAL > ERROR > WARN > INFO > DEBUG > ALL (低) -->
        <!--限制日志记录级别-->
        <level value="ALL"/>
        <appender-ref ref="rollingAppender" />
        <appender-ref ref="AdoNetAppender" />
    </root>


</log4net>

--打印日志调用

using Microsoft.AspNetCore.Mvc;

namespace Advanced.NET6.Project.Controllers
{
    public class SecondController : Controller
    {
        private readonly ILogger<SecondController> _logger;
        private readonly ILoggerFactory _loggerFactory;


        public SecondController(ILogger<SecondController> logger, ILoggerFactory loggerFactory)
        {
            //方式一
            this._logger = logger;
            this._logger.LogInformation($"{this.GetType().Name}被_logger构造了。。。");

            //方式二
            this._loggerFactory = loggerFactory;
            ILogger<SecondController> logger2 = this._loggerFactory.CreateLogger<SecondController>();
            logger2.LogInformation($"{this.GetType().Name}被logger2构造了。。。");
        }

        public IActionResult Index()
        {
            //方式三
            ILogger<SecondController> logger3 = this._loggerFactory.CreateLogger<SecondController>();
            logger3.LogInformation($"{this.GetType().Name}被logger3执行了。。。");

            this._logger.LogInformation("Index 被执行了。。。");
            return View();
        }
    }
}