.NET Core下使用Log4Net记录日志的方法步骤
时间：2022-01-27 08:49:37|栏目：.NET代码|点击： 次
Log4Net 相信大家都很熟悉了，算是比较主流和著名的日志组件了。
开源地址： https://github.com/apache/logging-log4net
最佳实践
在项目中添加组件包
Install-Package log4net
添加 log4net.config 文件
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
</configSections>
<log4net debug="false">
<appender name="info" type="log4net.Appender.RollingFileAppender,log4net">
<param name="File" value="log4net/info/" />
<param name="AppendToFile" value="true" />
<param name="MaxSizeRollBackups" value="-1"/>
<param name="MaximumFileSize" value="5MB"/>
<param name="RollingStyle" value="Composite" />
<param name="DatePattern" value="yyyyMMdd\\HH".log"" />
<param name="StaticLogFileName" value="false" />
<layout type="log4net.Layout.PatternLayout,log4net">
<param name="ConversionPattern" value="%n
{
"system": "Meowv.Blog",
"datetime": "%d",
"description": "%m",
"level": "%p",
"info": "%exception"
}" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="INFO" />
<levelMax value="INFO" />
</filter>
</appender>
<appender name="error" type="log4net.Appender.RollingFileAppender,log4net">
<param name="File" value="log4net/error/" />
<param name="AppendToFile" value="true" />
<param name="MaxSizeRollBackups" value="-1"/>
<param name="MaximumFileSize" value="5MB"/>
<param name="RollingStyle" value="Composite" />
<param name="DatePattern" value="yyyyMMdd\\HH".log"" />
<param name="StaticLogFileName" value="false" />
<layout type="log4net.Layout.PatternLayout,log4net">
<param name="ConversionPattern" value="%n
{
"system": "Meowv.Blog",
"datetime": "%d",
"description": "%m",
"level": "%p",
"info": "%exception"
}" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="ERROR" />
<levelMax value="ERROR" />
</filter>
</appender>
<root>
<level value="ALL"></level>
<appender-ref ref="info"/>
<appender-ref ref="error"/>
</root>
</log4net>
</configuration>
控制台项目
using log4net;
using log4net.Config;
using System;
using System.IO;
using System.Reflection;
namespace ConsoleAppDemo
{
class Program
{
static void Main(string[] args)
{
var log4netRepository = LogManager.GetRepository(Assembly.GetEntryAssembly());
XmlConfigurator.Configure(log4netRepository, new FileInfo("log4net.config"));
ILog log = LogManager.GetLogger(log4netRepository.Name, "NETCorelog4net");
log.Info("NETCorelog4net log");
log.Info("test log");
log.Error("error");
log.Info("linezero");
Console.ReadKey();
}
}
}
AspNetCore项目
新建一个静态类，写一个扩展方法 UseLog4Net() ，用于 log4net 初始化。
public static class Log4NetExtensions
{
public static IHostBuilder UseLog4Net(this IHostBuilder hostBuilder)
{
var log4netRepository = LogManager.GetRepository(Assembly.GetEntryAssembly());
XmlConfigurator.Configure(log4netRepository, new FileInfo("log4net.config"));
return hostBuilder;
}
}
扩展方法返回 IHostBuilder 对象，这样可以链式调用，美化代码，然后在 Program.cs 中使用扩展方法 UseLog4Net() 。
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
namespace WebAppDemo
{
public class Program
{
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseStartup<Startup>();
}).UseLog4Net();
}
}
配置完成，然后在任意地方写入日志即可。
using log4net;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
namespace WebAppDemo.Controllers
{
[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
private static readonly string[] Summaries = new[]
{
"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};
private readonly ILog _log;
public WeatherForecastController()
{
_log = LogManager.GetLogger(typeof(WeatherForecastController));
}
[HttpGet]
public IEnumerable<WeatherForecast> Get()
{
_log.Info("Hello, this is a Weather api!");
_log.Warn("Wran !!!");
_log.Error("Controller Error");
var rng = new Random();
return Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = rng.Next(-20, 55),
Summary = Summaries[rng.Next(Summaries.Length)]
})
.ToArray();
}
}
}
