.net8系列-05图文并茂手把手教你.NET Core 下使用 Log4Net 记录日志，配置日志组件log4net

log4net是什么？

log4net是Apache软件基金会为.NET平台开发的一个日志记录库。它是Apache log4j框架的.NET移植版本，属于Apache Logging Services项目的一部分。

为什么使用log4net？

log4net设计用于帮助.NET应用程序的开发者控制日志信息的生成过程，使得日志信息可以根据配置被输出到多种目的地，包括控制台、文件系统、数据库、电子邮件、Windows事件日志等。

log4net有什么特点？

分级日志级别：支持DEBUG、INFO、WARN、ERROR、FATAL等多个日志级别，允许开发者精细控制输出哪些信息。
灵活的配置：强大的XML配置文件支持，可以在不修改代码的情况下调整日志行为。
多种输出目标：支持多种日志信息的目的地，易于扩展。
定制化布局：可以定制日志信息的格式，如添加时间戳、线程信息等。
性能优化：通过缓冲和异步写入等机制减少日志记录对应用程序性能的影响。

log4net怎么用？

安装log4net解决方案包

安装Microsoft.Extensions.Logging.Log4Net.解决方案包

编写配置文件

xiaojinWebApplication\xiaojinWebApplication\configFile\log4net.Config

<?xml version="1.0" encoding="utf-8"?>
<log4net><!-- Define some output appenders --><appender name="rollingAppender" type="log4net.Appender.RollingFileAppender"><file value="log4\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" /><!--日志最大个数,都是最新的--><!--rollingStyle节点为Size时,只能有value个日志--><!--rollingStyle节点为Composite时,每天有value个日志--><maxSizeRollBackups value="20" /><!--可用的单位:KB|MB|GB--><maximumFileSize value="3MB" /><!--置为true,当前最新日志文件名永远为file节中的名字--><staticLogFileName value="true" /><!--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><layout type="log4net.Layout.PatternLayout"><conversionPattern value="%date [%thread] %-5level %logger - %message%newline"/></layout></appender><!--SqlServer形式--><!--log4net日志配置：http://logging.apache.org/log4net/release/config-examples.html --><appender name="AdoNetAppender_SqlServer" type="log4net.Appender.AdoNetAppender"><!--日志缓存写入条数 设置为0时只要有一条就立刻写到数据库--><bufferSize value="0" /><connectionType value="System.Data.SqlClient.SqlConnection,System.Data.SqlClient, Version=4.6.1.3, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" /><connectionString value="Data Source=PC-202206030027;Initial Catalog=LogManager;Persist Security Info=True;User ID=sa;Password=sa123" /><commandText value="INSERT INTO Log4Net ([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><!--控制级别，由低到高: ALL|DEBUG|INFO|WARN|ERROR|FATAL|OFF--><!--OFF:0--><!--FATAL:FATAL--><!--ERROR: ERROR,FATAL--><!--WARN: WARN,ERROR,FATAL--><!--INFO: INFO,WARN,ERROR,FATAL--><!--DEBUG: INFO,WARN,ERROR,FATAL--><!--ALL: DEBUG,INFO,WARN,ERROR,FATAL--> <priority value="ALL"/><level value="INFO"/><appender-ref ref="rollingAppender" /><appender-ref ref="AdoNetAppender_SqlServer" /></root>
</log4net>

暂时注释数据库日志，等到我们链接数据库后我们再进行使用

注释root里的AdoNetAppender_SqlServer

	<root><!--控制级别，由低到高: ALL|DEBUG|INFO|WARN|ERROR|FATAL|OFF--><!--OFF:0--><!--FATAL:FATAL--><!--ERROR: ERROR,FATAL--><!--WARN: WARN,ERROR,FATAL--><!--INFO: INFO,WARN,ERROR,FATAL--><!--DEBUG: INFO,WARN,ERROR,FATAL--><!--ALL: DEBUG,INFO,WARN,ERROR,FATAL--> <priority value="ALL"/><level value="INFO"/><appender-ref ref="rollingAppender" /><!-- <appender-ref ref="AdoNetAppender_SqlServer" /> --></root>

配置NLog.Config

xiaojinWebApplication\xiaojinWebApplication\configFile\NLog.Config

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"autoReload="true"throwExceptions="false"internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log"><!-- optional, add some variableshttps://github.com/nlog/NLog/wiki/Configuration-file#variables--><variable name="myvar" value="myvalue"/><!--See https://github.com/nlog/nlog/wiki/Configuration-filefor information on customizing logging rules and outputs.--><targets><!--add your targets hereSee https://github.com/nlog/NLog/wiki/Targets for possible targets.See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.--><target name="AllDatabase" xsi:type="Database"dbProvider="System.Data.SqlClient.SqlConnection, System.Data.SqlClient"connectionString="Data Source=PC-202206030027;Initial Catalog=LogManager;Persist Security Info=True;User ID=sa;Password=sa123"commandText="insert into dbo.NLog (Application, Logged, Level, Message,Logger, CallSite, Exception) values (@Application, @Logged, @Level, @Message,@Logger, @Callsite, @Exception);"><parameter name="@application" layout="AspNetCoreNlog" /><parameter name="@logged" layout="${date}" /><parameter name="@level" layout="${level}" /><parameter name="@message" layout="${message}" /><parameter name="@logger" layout="${logger}" /><parameter name="@callSite" layout="${callsite:filename=true}" /><parameter name="@exception" layout="${exception:tostring}" /></target><target xsi:type="File" name="allfile" fileName="NLog\nlog-all-${shortdate}.log"layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" /><!--同样是将文件写入日志中，写入的内容有所差别，差别在layout属性中体现。写入日志的数量有差别，差别在路由逻辑中体现--><target xsi:type="File" name="ownFile-web" fileName="NLog\nlog-my-${shortdate}.log"layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" /><target xsi:type="Null" name="blackhole" /><!--Write events to a file with the date in the filename.<target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log"layout="${longdate} ${uppercase:${level}} ${message}" />--></targets><rules><logger name="*" minlevel="Trace" writeTo="AllDatabase" /><!-- add your logging rules here --><!--路由顺序会对日志打印产生影响。路由匹配逻辑为顺序匹配。--><!--All logs, including from Microsoft--><logger name="*" minlevel="Trace" writeTo="allfile" /><!--Skip Microsoft logs and so log only own logs--><!--以Microsoft打头的日志将进入此路由，由于此路由没有writeTo属性，所有会被忽略--><!--且此路由设置了final，所以当此路由被匹配到时。不会再匹配此路由下面的路由。未匹配到此路由时才会继续匹配下一个路由--><logger name="Microsoft.*" minlevel="Trace"  final="true" /><!--上方已经过滤了所有Microsoft.*的日志，所以此处的日志只会打印除Microsoft.*外的日志--><logger name="*" minlevel="Trace" writeTo="ownFile-web" /><!--Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace)  to "f"<logger name="*" minlevel="Debug" writeTo="f" />--></rules>
</nlog>

设置编译属性

右键两个配置文件，改为始终编译

配置日志生效逻辑

在Program.cs文件中注册

// log4net---start
builder.Logging.AddLog4Net("configFile/log4net.Config");
// log4net---end

日志使用：构造函数注入

在测试接口文件中添加如下代码（我这个已经有了哦）

 private readonly ILogger<CommonInfoController> _logger;public CommonInfoController(ILogger<CommonInfoController> logger){_logger = logger;}

添加日志测试代码

 public CommonInfoController(ILogger<CommonInfoController> logger){_logger = logger;_logger.LogInformation(" LogInformation; this is CommonInfoController 构造函数~");_logger.LogError("LogError: this is CommonInfoController 构造函数~");_logger.LogWarning("LogWarning: this is CommonInfoController 构造函数~");_logger.LogDebug("LogDebug:this is CommonInfoController 构造函数~");}

第二种用法

   private readonly ILogger<CommonInfoController> _logger; // 方案一private readonly ILoggerFactory _ILoggerFactory; // 方案二public CommonInfoController(ILogger<CommonInfoController> logger, ILoggerFactory iLoggerFactory){_logger = logger;_logger.LogInformation("方案一 LogInformation; this is CommonInfoController 构造函数~");_logger.LogError("方案一LogError: this is CommonInfoController 构造函数~");_logger.LogWarning("方案一LogWarning: this is CommonInfoController 构造函数~");_logger.LogDebug("方案一LogDebug:this is CommonInfoController 构造函数~");_ILoggerFactory = iLoggerFactory; // 方案二ILogger<CommonInfoController> _loger2 = _ILoggerFactory.CreateLogger<CommonInfoController>();_loger2.LogInformation("方案二LogInformation; this is CommonInfoController 构造函数~");_loger2.LogError("方案二LogError: this is CommonInfoController 构造函数~");_loger2.LogWarning("方案二LogWarning: this is CommonInfoController 构造函数~");_loger2.LogDebug("方案二LogDebug:this is CommonInfoController 构造函数~");}

接口中记录日志

/// <summary>
/// 测试接口01
/// </summary>
/// <returns></returns>
[HttpGet(Name = "getCommonInfo")]
public CommonInfo getCommonInfo()
{_logger.LogInformation("测试接口01~");_logger.LogError("测试接口01~");_logger.LogWarning("测试接口01~");_logger.LogDebug("测试接口01~");return new CommonInfo{Date = DateOnly.FromDateTime(DateTime.Now),Text = "getCommonInfo"};
}

启动项目

调用接口

查看日志

根据我们的配置项，日志在这个地方存储：“\xiaojinWebApplication\bin\Debug\net8.0\log4\log.txt”

2024-04-30 01:29:51,143 [1] INFO  Microsoft.Hosting.Lifetime - Now listening on: http://localhost:5064
2024-04-30 01:29:51,153 [1] INFO  Microsoft.Hosting.Lifetime - Application started. Press Ctrl+C to shut down.
2024-04-30 01:29:51,154 [1] INFO  Microsoft.Hosting.Lifetime - Hosting environment: Development
2024-04-30 01:29:51,155 [1] INFO  Microsoft.Hosting.Lifetime - Content root path: C:\Users\testDemo\net-demo\xiaojinWebApplication\xiaojinWebApplication
2024-04-30 01:30:17,271 [7] INFO  xiaojinWebApplication.Controllers.CommonInfoController - 方案一 LogInformation; this is CommonInfoController 构造函数~
2024-04-30 01:30:17,279 [7] ERROR xiaojinWebApplication.Controllers.CommonInfoController - 方案一LogError: this is CommonInfoController 构造函数~
2024-04-30 01:30:17,281 [7] WARN  xiaojinWebApplication.Controllers.CommonInfoController - 方案一LogWarning: this is CommonInfoController 构造函数~
2024-04-30 01:30:17,282 [7] INFO  xiaojinWebApplication.Controllers.CommonInfoController - 方案二LogInformation; this is CommonInfoController 构造函数~
2024-04-30 01:30:17,285 [7] ERROR xiaojinWebApplication.Controllers.CommonInfoController - 方案二LogError: this is CommonInfoController 构造函数~
2024-04-30 01:30:17,287 [7] WARN  xiaojinWebApplication.Controllers.CommonInfoController - 方案二LogWarning: this is CommonInfoController 构造函数~
2024-04-30 01:30:17,289 [7] INFO  xiaojinWebApplication.Controllers.CommonInfoController - 测试接口01~
2024-04-30 01:30:17,290 [7] ERROR xiaojinWebApplication.Controllers.CommonInfoController - 测试接口01~
2024-04-30 01:30:17,291 [7] WARN  xiaojinWebApplication.Controllers.CommonInfoController - 测试接口01~