我们在开发任何项目过程中，记录各种日志是太正常不过的事情。没有日志记录的项目，也不可能放心进入生产环境运行。因此日志的记录，是必须要做的。
在.NET开发中，log4net是个常用的日志组件。本文简单记录下在ASP.NET Core中使用log4net来写日志。
1.Nuget中引入log4net组件
控制台执行以下命令：
Install-Package log4net Install-Package Microsoft.Extensions.Logging.Log4Net.AspNetCore
2.在项目根目录下新建log4net的配置文件log4net.config，并将其设置为始终复制。
项目根目录下创建文件夹CfgFile,在添加XML文件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=.\SQLEXPRESS;Initial Catalog=LogManager;Persist Security Info=True;User ID=sa;Password=a123456!" />
<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>
3.在Controller中输出日志内容：
public class SecondController : Controller
{
private readonly ILogger<SecondController> _Logger;
private readonly ILoggerFactory _LoggerFactory;
public SecondController(ILogger<SecondController> logger, ILoggerFactory loggerFactory)
{
this._Logger = logger;
this._Logger.LogInformation($"{this.GetType().Name} 被构造了。。。_Logger");
this._LoggerFactory = loggerFactory;
ILogger<SecondController> _Logger2 = this._LoggerFactory.CreateLogger<SecondController>();
_Logger2.LogInformation($"{this.GetType().Name} 被构造了。。。_Logger2");
}
public IActionResult Index()
{
ILogger<SecondController> _Logger3 = this._LoggerFactory.CreateLogger<SecondController>();
_Logger3.LogInformation($"Index 被执行了。。。。。_Logger3");
this._Logger.LogInformation($"Index 被执行了。。。");
return View();
}
public IActionResult Level()
{
_Logger.LogDebug("this is Debug");
_Logger.LogInformation("this is Info");
_Logger.LogWarning("this is Warn");
_Logger.LogError("this is Error");
_Logger.LogTrace("this is Trace");
_Logger.LogCritical("this is Critical");
return new JsonResult(new { Success = true });
}
public object GetData()
{
return new
{
Id = 123,
Name = "Richard"
};
}
}
以上配置的log4net,实现了.txt格式日志文件的写入，还有日志写库。
输出日志如下：
2022-11-12 22:29:46,368 [.NET ThreadPool Worker] INFO Advanced.NET6.Project.Controllers.SecondController - SecondController 被构造了。。。_Logger
2022-11-12 22:29:46,377 [.NET ThreadPool Worker] INFO Advanced.NET6.Project.Controllers.SecondController - SecondController 被构造了。。。_Logger2
2022-11-12 22:29:55,460 [.NET ThreadPool Worker] INFO Advanced.NET6.Project.Controllers.SecondController - Index 被执行了。。。。。_Logger3
2022-11-12 22:29:55,465 [.NET ThreadPool Worker] INFO Advanced.NET6.Project.Controllers.SecondController - Index 被执行了。。。
执行以下SQL语句，查询下写入库中的日志：
select * from log4net order by Date desc
得到如下的数据列表：
Id Date Thread Level Logger Message Exception
1009 2022-11-12 22:29:55.467 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController Index 被执行了。。。
1008 2022-11-12 22:29:55.460 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController Index 被执行了。。。。。_Logger3
1007 2022-11-12 22:29:46.377 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController SecondController 被构造了。。。_Logger2
1006 2022-11-12 22:29:46.370 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController SecondController 被构造了。。。_Logger
1004 2022-11-12 22:28:46.443 1 INFO Microsoft.Hosting.Lifetime Hosting environment: Development
1003 2022-11-12 22:28:46.437 1 INFO Microsoft.Hosting.Lifetime Application started. Press Ctrl+C to shut down.
1002 2022-11-12 22:28:46.160 1 INFO Microsoft.Hosting.Lifetime Now listening on: http://localhost:5999
8 2022-11-11 09:55:40.147 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController Index 被执行了。。。
7 2022-11-11 09:55:40.140 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController Index 被执行了。。。。。_Logger3
6 2022-11-11 09:55:37.507 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController SecondController 被构造了。。。_Logger2
5 2022-11-11 09:55:37.493 .NET ThreadPool Worker INFO Advanced.NET6.Project.Controllers.SecondController SecondController 被构造了。。。_Logger
3 2022-11-11 09:55:25.780 1 INFO Microsoft.Hosting.Lifetime Hosting environment: Development
2 2022-11-11 09:55:25.773 1 INFO Microsoft.Hosting.Lifetime Application started. Press Ctrl+C to shut down.
1 2022-11-11 09:55:25.630 1 INFO Microsoft.Hosting.Lifetime Now listening on: http://localhost:5999
log4net的使用，就这样完事啦...
标签：log4net,Core,Asp,INFO,SecondController,2022,11,NET,Logger From： https://www.cnblogs.com/michael999/p/16884922.html